Rodolfo,

Typically it happens when the WS crashes with tables open especially when records are being appended resulting in a corruption of the table header which among other things hold info. about no of records in the table.

It's common and recommended to have a utility program that reindex and rebuild tags for each table which should be run every week to 2 weeks depending on the usage of the App. In some rare cases reindex and pack commands don't solve the problem and a dumping and recreation of tags have to take place. This has been an ongoing problem and limitation with FP tables since the begining of time and so far hasn't been dealt with which is a serious limitation to VFP as a backend compared to more solid backends like MS SQL or Oracle.

You could try to minimize that occurance by opening tables as needed in case you open a bunch of tables in launching the App.