I have seen security programs stop that service before, maybe turn off your Antivirus or whatever security programs you have and try starting the service or rebooting.
Trying to bring an old Poweredge 2800 up-to-date ... A few weeks ago I updated the OMSA on this machine from 5.3.0 to 6.4.0, mostly in the hope that it might highlight any out-of-date firmware or drivers. Since then, the service "DSM SA Data Manager" crashes at start time.  100% reproducible, at boot or any time thereafter.  Typical symptoms are: Event Type:    ErrorEvent Source:    Application ErrorEvent Category:    (100)Event ID:    1000Date:        17/01/2011Time:        09:39:25User:        N/AComputer:    ADMINDescription:Faulting application dsm_sa_datamgr32.exe, version 5.9.4.1008, faulting module unknown, version 0.0.0.0, fault address 0x00000000.   The only similar reference I found on here is this one: [URL] ... which suggests manually installing Bios, Drac and Perc updates, then re-installing. Any other, less generic, suggestions please ?    
OMSA 6.4.0 "data manager" service crash on PE2800