Guys we were having this same problem for over 3 weeks without finding a fix, and then i found this thread....
I decided to have a look at our server as i couldn't remember installing SQL on to the server which wouldn't backup and found a service called "SQL Server VSS Writer". As i said i didn't remember installing SQL on to this server so i had a look and found this is actually packaged with Windows Server 2003 (which is the OS on the server in question). The up shot of this whole story is, i stopped this service and was able to backup the Drives withour having to upgrade to 10dor cause any detrimental effects to services on the server.
An odd thing is, this server was working fine up until about 3 to 4 weeks ago and i know none of our guys installed the service or anything else on this server, so why the sudden problem, i'm thinking along the lines of a Microsoft Auto Update or something, but hey not bovvered it now works.
And there was much rejoicing..
Many thanks to you guys for discovering it was something to do with SQL.
Message Edited by oOEggmanOo on 07-09-200703:41 AM