I'm getting this error now too.

Msg 50000, Sev 18, State 1: SLS Error: No Result XML returned from Engine. (Possible abend/termination) [SQLSTATE 42000]

It just started recently after a reboot of the box to swap out some questionable RAM. Latest OS updates were installed as well and the error started right after. Before the upgrade the backups ran without error.

My box is MS Windows Server 2003 R2, Standard x64 Edition Service Pack 2

Microsoft SQL Server 2005 Enterprise Edition (64-bit) on Windows NT 5.2 (Build 3790: Service Pack 2)