Windows Server 2008 r2 backup

Hello, I am trying to backup a Windows Server 2008 r2 VM running on ESXi 5.0.0.
When I run the Windows Server Backup snap-in it returns the '2155348129' error code. Looking around this seems to be caused byt the OS partition not being active, however since it is a VM I'm afraid changing the active partition will cause it not to boot correctly. The active partition at the moment is a 100MB "system reserved" partition, which i believe contains ESXi "stuff". Any ideas on how to fix it and make a backup of the machine?
It seems weird that MS didn't consider virtualized windows machines when they wrote the backup snap-in. Or did I get something wrong?

I'd be grateful for any help.

Never mind, solved.
It wasn't the partition not being active, it was also trying to backup a non-existing SQL Server instance.
No idea where it got it from...