I uninstalled RAWS from 10 of the servers, it appeared to work initially, as I was able to perform a successful backup (see attachment), but then when I ran a scheduled job of the same servers 30 mins later, it failed again on some of the servers with the 'e000959a - An attempt to take a snapshot of a virtual machine failed because it was unable to quiesce an application.' error message (see attachment2).
I did notice after re-installing that in Add/Remove Programs some of the install sizes are different on different servers, (see attachment 3 & 4), some at 184mb, some at 200mb, even though they are all Windows 2003 R2, all the same version of RAWS, and all installed from the same BE 2010 R3 server!
The file versions are the same - 13.0.5204.125 - however the file sizes & dates are different - working server beremote - 1.76mb and 13th Feb 2012 vs failing server 1.21mb and 1st March 2012 (see attached pic)!
Check the beremote.exe on the media server. Make sure that the beremote.exe on the remote server correspond to the beremote.exe on the media server. If necessary, uninstall the RAWS and push out the RAWS again.