This is often the result of a dangling object reference.
David FrankenBach (sp?) has a utility on his site. Check is profile for the address.

>I subclassed the textbtns class of FFC and I use it in my forms. 'Txtbtns' class has buttons for navigation,add,edit,delete, and exit. The exit button has one line of code - 'thisForm.Release'.
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>Intermittently, pressing the exit button does not close the form. The 'X' button on the top right corner of the titlebar gets disabled. I can see the exit button getting pressed (visually). I can not imagine that the button press code is not being executed, since it works most of the time. I can't use the debugger since it only happens very randomly. So, is there any other reason for which the 'thisForm.Release' command would not work. Any other ideas?
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>Thanx
>Gnana