I borrowed a 2gig card from a friend which turned out to be one of the buggy cards unfriendly to the Canon Rebel XT.
When I attempted to download photos into my Mac, it crashed repeatedly, even when I used the Lexar Image Rescue software.
It has affected the database and now when I try to rate or label a file, I get warning messages like this one:
"Labels and ratings are stored in XMP Metadata. If a file has no way to store XMP, they be stored in cache only."

I tried to reset Bridge to default settings to restore the lost functionality and got this message:
"There was a problem with the database and ".loptions" was not updated correctly. This may affect searches."

What next, fellow luminaries???

Try the same things on another Mac? Or even a PC?
And if that doesn't work there are those data rescue firms (probably a geek in an attic), who'll charge you of course.
Main thing is you rescue whatever images can be rescued, no?
Because I assume you won't be using that card in your camera again, will you?