Well, I may have finally found what my C0000005 problem has been. After days of testing for this problem alone, I've been able to recreate it. I got a more meaningful error message this time, and I have determined that it involves a simple index file being corrupted-- reindexing(DEL *.IDX and then INDEX ON again) fixes the problem. The only index open at this time(the one at fault) is a simple index on a logical field(PAID). The PAID field is changed in only 3-4 places in the program-- only once per record number. All it does is change it to .T. after locking the record(only if RLOCK returns true, of course). What could I be doing wrong to corrupt this index? Are there some rules in updating index keys that I'm just not following? Any ideas? Thanks.