Just a follow up, for I was just suffering this today.

As Dragan said, it seems that VCX + Property Sheet + Functions + Cache = Bad Idea, for whatever function you put in the property sheet will only be evaluated once, and it's value is then repeated to all new instances of the class, until a clear class is issued (and all instances previously killed). To see this easily, just create a new class, let's call it PSTextBox, based on textbox and leave everything default but value, where you put, for example =Seconds() (In the property sheet). Now put this textbox based object in a form and run it, the first time you'll get the correct value, but upon running another instance of the form, or even closing this form and running it again, the Textbox's value will not change, it will retain it's value. To force a new evaluation, you need to issue a "clear class PSTextBox" after closing all running instances.