Can't open Map / Failed to load Source Schema

Hello NG,

since today I have a problem in my Biztalk Solution. I can't open any
Map, everytime I try to open one there comes an error Message like
"Failed to load the source schema".
It seems that it is the same problem as decriped in this post:

http://groups.google.com/group/microsoft.public.biztalk.general/browse_thread/thread/b6bf32961dc25a74/60d95c21b4615b15?hl=en#60d95c21b4615b15

If I remove the c# project from the solution everything works fine.
Does anybody has fixed that problem, or has tried this fix to solve
it: http://support.microsoft.com/kb/926344?

Thanks and Regards,
Lorenz
.