Vista Media Center dies when viewing videos

When I run Windows Media Center on my PC (not through my 360) whenever I open
the video library, MC crashes and sometimes I get a message "Com Surrogate
Failed". I've searched around on here and haven't seen anyone else with this
problem. It *seems* to have happened when I tried to edit some videos from
my Canon camera (SD850is) so that they would play. Strangely enough some of
the videos play and other more recent ones don't, so I took one file and
tried to save it off as two different formats with Nero (AVI, which is what
it was originally, and .mpg). Once I saved off these new versions of the
files, MC never worked for the video library again. I first tried renaming
them thinking the fact that Nero put in two dots in the name might have
screwed up some indexing scheme in MC, but that didn't help. Then I removed
all of the videos from the Windows Media Player library, but that didn't seem
to help either. Any other ideas? Supposedly my machine is completely up to
date, but I can't find the search string "com surrogate" anywhere in the
knowledge base which seems strange to me, so maybe this is a relatively new
bug...
Thanks in advance for any new ideas!
-Bob in Winchester, MA