As you asked, I'll try, but I won't be able to do so untill I get back from Manchester.
The reason I said the logs were no good was because they were often well over a megabyte big, and when the windows popup came telling me that "Media Center has encountered a problem and needs to close", MC continued to build thumbs quite happily until I clicked OK on the windows message.
Then, when I looked at the logs, the "unhandled exception: program crashing" lines were buried away in the middle of reams of thumbnailing chatter.
For the record, it crashed on a different file each time. I had been hoping it would pinpoint a single file that was causing a problem, but if only things could be that simple!!
Also, there was nothing obviously untoward around and about the crashing lines. the thumbnailing chatter repeating normally for each file, then the two crash lines would appear, and the thumbnailing continues, until I OK the windows message, at which point, the log ends abruptly.
Let me know if that's enough info to go on, or do you think that a logfile might be more help?
-marko