I'm sorry, but I'm a bit confused now.
In the original post, you stated: "It seems to happen on a form that gets a lot of code mods, after so many mods the timer just quits working". And your recent post, "consists of one form, which runs a timer event ... only thing it does is check for a file".
Can you post the Timer Event handler? What does the program do is the check fails?, check suceeds?
Good Luck
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As a circle of light increases so does the circumference of darkness around it. - Albert Einstein