Need Help with Stopping a command

I have a small search program that goes through a ascii file. the file is about 70000 records so it takes a minute or so to parse. They want me to be make it so that once the user types in the search criteria and click the search button ( a command button ( to be able to cancel the search. I’ve tried having all the code behind the command1_click button and having another button to click that creates a value to stop it. However once it’s executing the code it won’t let the user click anthinguntil it’s finished. I’ve also tried useing a sub procedure and the results stayed the same. I’m using VB 4.0 Thanks

Dwane