I have encountered this three separate times now, and cannot find a specific cause OR cure. Can anyone shed light on this problem?

Clients running a VFP based accounting system, using DBF files, both on Novell servers. When DBF files get large (100mb index on one, 270mb DBF & 36mb index on the other), when you reindex the files either manually or within the accounting system, the indexes are corrupt, but no errors during the reindex process.

Most recently, I found that the data file was crashing on the sixth index tag, which was a logical index. I was able to create all of the first five index tags manually, one at a time, close then reopen the file each time. Upon creating the 6th tag, when reopening the file, I get a windows error "This program has caused an illegal operation and will be shut down in VFP.EXE"

In all three cases, copying out about a third of the data from the beginning (older data) of the file completely cured the problem immediately. This is not the desired fix though.

Can someone tell me how to cure these for good?

Thanks