We recently went through the same issue. First of all this is not a NetBackup problem so don't take a lot of heat for it :)

 

Now the solution. There is a VSS rollup package from MS which fixes this problem. You can get it from http://support.microsoft.com/kb/940349

If your Windows team builds the servers using RIS or some other means of scripted installation you should check the following technote:

http://seer.entsupport.symantec.com/docs/315898.htm. This issue caused the backups to start & not transfer any data & remain active for a few days. This was post VSS rollup install.

Also check out the following technote, they might also help:

 

Following article is just helpful in troubleshooting VSS: 

 

Hope this helps.

 

Khurram

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