I do not understand this but it seems that the USED() function either has a bug in it and can't see that the file is already open, or...? Has anyone else dealt with this problem, or am I imagining this?

*The CERTS table is already open.
IF !USED("E:\PRODUCTION\DATA\CERTS")
   * The program blows up right and says "file is in use".
   USE E:\PRODUCTION\DATA\CERTS EXCLUSIVE IN 0
ENDIF

I don't think that the USED() function is working right, because if it were working right, it would not have gone into the IF !USED() condition.