ie have cell a1 as the validation with a value of Y to run the loop and anything else to not run the loop and then enclose the loop statement in an if statement so that if cell a1 has a value of Y it runs the loop, if not it just goes to the end of the macro.
I have got the same senario in a file at work and it doesn't lock up my PC... can't quite remember how I wrote it though and I'm not back in the office until 05/01/04. I think it was basically as Vog has said, but I'd used the GoTo code instead of loop, so when it got to the end it went back to the top.
Perhaps its locking because its every 2 secs, by the time the macro has run, the 2 secs has probably passed so it runs again. What happens if you set it to say 30 secs?
Reddwarfcrew- would like to try the goto method if you can get it to me. If you could give me more details as I am not an expert in writing macros. Have tried various times in the macro, but while it is wating for the time everything locks.