You may run across an error in DPM server that includes “insufficient system resources exist” in the backup job error. When I initially approached this issue, I was scouring the Microsoft site for ways to increase system resources. I think I applied every possible registry entry to deal with the situation. Problem is, it wasn’t an actual system resource issue, it was an antivirus issue.
Trend Micro by default, seems to install a service call “Intelliscan”. The “Intelliscan” option in OfficeScan and Worry Free Advanced, and probably other products, seems to cause a number of issues, one of which is often system slowness (http://esupport.trendmicro.com/Pages/The-scanner-is-very-slow-when-the-OfficeScan-7.0-Real-time-Scan-option.aspx)
Just for grins, after applying a bunch of registry hacks to no avail, I disabled antivirus altogether to start.. when the backups succeeded, I enabled antivirus, but this time without intelliscan… still had good backups.
Lesson learned, some times it’s the easy stuff. Disabling antivirus during a system problem is often step 1. Was more like step 101 but at least it fixed the issue.