>In the UNLOAD event of the form I call a method from the class.
>I get an error message, "Class myclass doesn't exist"

Yep, you can use the Event Viewer to see that all the controls Destroy() after the Form's Destroy() and before the Unload()

>Is this the normal behaviour? Looks like it has been already released by the time I try to call one of the methods from it. All I have in that method is: DO main1menu.mpr CLEAR EVENTS THISFORM.Release()

Why are you calling a method with Thisform.Release() in the Unload()?