>I am running a VFP 6.0 app on a network which is using the same tables I am using. The other app uses the files exclusively. I need to be able to check if the files (cust.dbf) is in use by another computer so my code doesn't bomb out when it goes to to a USE command. I tried ISFLOCKED() but it needs an alias and I can't create the alias without issuing the USE command. HELP!

ISFLOCK() will tell you if you have a file lock on the file, not other people. The best thing is to trap for the error in an error method or your ON ERROR handler.