One of the top issues faced by us at PSS is System Attendant Service not starting
I have tried to put all the steps that I am aware of. Check the link below.
Cheers
Allwyn.


http://exchangeserverinfo.net/how_to_troubleshoot_system_atten.htm



Gathering Required Information

Is the Service in a starting or Stopping state
When did the problem started
How many DC and GC are there
How did the problem started was  Disaster recovery of the Exchange Server performed
Was any DC demoted or removed forcefully from the network
Were any Hotfixes or patches applied to the Server

Troubleshooting the issue

If the Server and if the Server is stuck at Applying Computer Setting. remove the network cable and check does the Server boots completely
If still doesn’t wait for some time so the Server boots completely,Stop all the Exchange Services change the startup type to Disable
Check what is the Account type used to start the Service by default it should be LOCALSYSTEM Account
The first step to try is enable diagnostic logging on the Dsacess Service for all the counters to Maximum except cache. If for some reason you are not able to open ESM you can enable logging for the same from the exchange Server registry the path for the same would be My Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Service\MsExchangeDsAccess\Diagnostic. Change the logging level to 5 for all except Cache
Check out for the below 2080 Event in the Application Log

                          Event ID     : 2080
                          Raw Event ID : 2080
                          Record Nr.   : 6018
                          Category     : Topology
                          Source       : MSExchangeDSAccess
                          Type         : Information
                          Generated    : 6/22/2005 2:41:44 AM
                          Written      : 6/22/2005 2:41:44 AM
                          Machine      : BLUEOX
                          Message      : Process MAD.EXE (PID=2416). DSAccess has discovered the f                   
                          following servers with the following characteristics:

                          (Server name | Roles | Reachability | Synchronized | GC capable | PDC |     
                           SACL right | Critical Data | Netlogon | OS Version)

                           In-site:
                           Servername1.Domain.com CD   7 7 1 0 0 1 7 1
                           Servername2.Domain.com CDG 7 7 1 0 0 1 7 1

What does it mean? and what to do

Roles | Reachability | Synchronized | GC capable | PDC | SACL right | Critical Data

Roles:
Roles mean that this server is capable of serving as a: D - DC, C - Config DC, G - GC (Make Sure the first server listed over here is a CDG if it is not Exchange Services will start sometimes but you may face a issue such as whenever you restart the server System Attendant servioce does not sstart automatically and it start manually)

Reachability:
Reachability means we can connect to the appropriate ports (389 & 3268) of a
            Server. It's a bit mask, 1 is GC, 2 is DC, 4 is CDC (You won find issues with this value

Synchronized:
Synchronized means that the IsSynchronzied (or IsGlobalCatalogReady) property is
            Set in the AD (we try to avoid out-of-sync servers). It's a bit mask too.

GC Capable:
Self explanatory

PDC:
The server acts in the PDC role (concept from the pre-AD era) it is always 0

SACL right:
A must have permissions set by RUS. except 0 everything is accepted if this is 0 follow below. steps

Critical Data:
We avoid the servers that miss certain objects (like server objects), unless it's a
            Cluster (where these objects don't exist rightfully).

The above 2080 event says that there are no SACL rights and these could be one reason why System Attendant Service is not Starting. try the below steps

1. Run DomainPrep or follow step 2

2. Open Domain Controller Security policy expand Local Policies and click on User Rights Assignment, on the right hand side double click on Manage Auditing and Security Log and check do we have Exchange Enterprise Server group added to it if not add it and then try starting the Exchange System Attendant Service.(Certain scenarios you may even see a SID over there this could be sometimes the exchange enterprise Servers group itself but because these groups must have been deleted it in error and ran Domain prep which has created a new exchange enterprise Servers group you can remove that SID and then try to start the System Attendant Service)

3. If still it doesn’t start check whether the Exchange Server is a member of Exchange Domain Servers group and Exchange Domain Servers in turn should be a member of exchange Enterprise Servers group.

If the above event would be something like this (which is shown below) and still the System Attendant Service is not starting there could be some permission issues. Check out is the Exchange Server object  added on the Exchange Server itself and has full control on it.
There could be issues where the above events says that the SACL right is there and you have checked the permission and its all good run policy test this will help us to check does we really have the SACL right there could be a group policy which is overriding it

                          Event ID     : 2080
                          Raw Event ID : 2080
                          Record Nr.   : 6018
                          Category     : Topology
                          Source       : MSExchangeDSAccess
                          Type         : Information
                          Generated    : 6/22/2005 2:41:44 AM
                          Written      : 6/22/2005 2:41:44 AM
                          Machine      : BLUEOX
                          Message      : Process MAD.EXE (PID=2416). DSAccess has discovered the f                   
                          Following servers with the following characteristics:

                          (Server name | Roles | Reachability | Synchronized | GC capable | PDC |     
                           SACL right | Critical Data | Netlogon | OS Version)

                           In-site:
                           Servername1.Domain.com CD   7 7 1 0 1 1 7 1
                           Servername2.Domain.com CDG 7 7 1 0 1 1 7 1

As always the following tools will always help you while troubleshooting System Attendant service not starting

1. Dcdiag (DC issues)
2. Policytest (Rights issue)
3. Netdiag (Network issues)
4. Nltest (Envioroment Information)
5. ExBPA (Tool you can download from Microsoft Web Site which gives you good details about Exchange)

Quick Steps if System Attendant Service does not start

1. Are Exchange Domain Servers and Enterprise Servers group in default Users OU
2. Does Exchange Domain Server group has the Exchangte Server account as the member
3. Does the Exchange Server account has Full control permission on the Server itself when you see the Security 
    page from ESM for the server
4.See the bbelow patch and make sure you are able to open all the files in this folder using Notepad if not take 
    ownership of the file and open it and then try to start SA
    C:\Documents and Settings\All Users\Application Data\Microsoft\Crypto\RSA\MachineKeys
5.Check the following attributes using ADSIEDIT

             (i).Expand Configuration, expand Configuration (CN=Configuration,DC=domain,DC=com), expand  
                 Services, and then expand Microsoft Exchange. 
             (ii). Expand OrganizationName, expand Administrative Groups, expand AdministrativeGroupName, and
                   then expand Servers
             (iii). Right-click Server Name, and then click Properties.on the attribute editor tab select the checkbox 
                    show only attributes that have values and see below attributes
                    msExchdatapath: (This is your Message Tracking path see that its a valid path)
                    msExchinstallpath : This is Exchange Server installation path confirm its valid
6.Check for the NIC speed is it 100/1000 Mbps and does it matches with your network Switch


There are many more reasons why SA will not start the reasons above are very common and will help you before going for any major resolution step


KB's for SA not starting

 280432 System Attendant Stops Working with a 9022 Event
 325674 System Attendant does not start after disaster recovery installation, and event ID 9022, 9149, 1005 
              messages occur 
325964 System Attendant Service Does Not Start, Error with a 9022 in Event Viewer