Card corruption, as fixed in the last OS2007 rev, was not a issue of cards getting unmounted or directories and files getting scrambled, but of the card controller being toasted for good - a card "corrupted" by that bug is dead for good, and cannot ever be revived or accessed any more.

Whatever you suffer from is obviously something different. Most likely is plain file system damage - memory cards usually pick up some degree of file system damage over the course of time, since they will frequently be hotplugged rather than ejected (even the tablets, which attempt to force an auto-eject through slot and rear panel switches, will fail to do so whenever an application is stuck). Or your rear panel has become loose - that magnet switch may unmount the internal card if the rear wiggles around too much.