If it cannot be duplicated, it is probably just an odd Windows occurance. Lock file has grown too large. Only two previous occurances. Delete any files it finds. Record locked by another user.
Index is out of date.
Corrupt table other than header. Alternately, a rebuild utility to restructure this file could be used, however one has yet to be found that works well for this error. In the BDE Administrator, click the Databases. The right side of the screen will display the path the Youth Enrollment program is using to access the datafiles. After November Update has been installed.