DPM SQL Issues

I had the following scenario:

• DPM 2007 Running on Windows Server 2003 R2 SP2 (x86)
• SQL 2005 Standard (x86) running on Windows Server 2008 (x64)

DPM would not protect the SQL databases, and kept giving errors that the protection was "inconsistant". There were lots of SQLVDI errors in event viewer, including a BADMEM error.
To cut a long story short, I found the fix was to replace the x86 version of SQL 2005 with an x64 version.