I have the most vexing problem and maybe I am missing something; but an intensive google search has not given any results. So I need to address myself to the experts :)
Here is the situation:
Some time ago, I created and published a simple custom form for Email; not realizing that it wasn't really necessary. Now, however, when I want to take it away from its location (Personal Forms Library) I no longer can forward or reply to mails without getting the message "The form you selected could not be displayed". The reason I want to delete this custom form is the email account that is associated with it which overwrites the definition under 'Tools, E-mail accounts' so that no matter which EMail account if want as the default, I always get the one from this form.
I therefore figure I need to find a way to disassociate this form but have not found the means to do this (I tried both the DocMessageClass and FormSwap utilities; but to no avail).
Thanks for the prompt reply ! Yes, the form cache was among the first things I tried but it did not solve the problem. As said before, I'm working on this for a while and so far the only thing I've come up with is to republish the form with the account that I have designated to be the default under 'Tools, Email accounts'. But it is not a very elegant solution.
I should have hoped that there is a way to "extricate" as it were a given custom form so that the system no longer needs it ....
Well, that's the whole point. Wehn I uninstall - that is: delete - the form I can no longer reply or forward. And if I reinstall - that is republish - it, it reverts back to the default account that is defined by it.
Clearly, there must be a link somewhere so that Outlook looks for that form when replying and forwarding (but not when creating a new mail). And if I knew how that link or association came about I probably could now undo it. But I'm not aware of making it the default for anything nor do I think that is is possible