>We have a VFP 5.0 app that runs on a file server. Several instances of the .exe may be running at the same time each accessing a separate VFP database, processing some files, and updating the database.
>We have recently encountered an "Internal Consistency Error" message box popping up while the application is running. All we can do at this point is to click the OK button on the message box after which the application shuts down. This results in some cdx files getting corrupted (some tags actually get wiped out of the cdx!) and the database becoming invalid.
>Any ideas on what could cause this are greatly appreciated.

Did you apply the latest service pack for VFP 5? Make also sure that runtimes on the file server are from the same service pack as your development version.