Similar experience here. Always when switching into thumbnail viewschemes; it always seemed like MC was dealing with thumbs as a few previously built panes (genres) would be empty. If I let MC "settle" first the problem was mollified but not eliminated - 10 minutes later I would lockup on another swicth.
I don't have time to do a rebuild yet, so I tried to do a few tweaks to my x64 system like updating chipset and SATA drivers, I also installed Win X64 SP2, found a nice new FFDSHOW version which plays real nice and now major hangups and lockups.
I know Jim's gonna kill me but I can't ditch x64 yet (don't have the time!), but I promise I will only report 32bit bugs from the laptop.
I realized I had about 3GB of thumbnails the other day, prior to this .203 release. I rebuilt and ended up with 624mb when all was said and done; things got really snappy after all this. Now this new build is rebuilding them again so I think things are really looking up - either way I don't plan on posting here about any further x64 problems - just happy things are stable so far.
I'll check out the tabs tonight.
DC