form locking up when calling form.show() from another thread

Question

Basically i have this weird problem. I create a form in the main thread, this form i can show and hide at will via a procedure i've written for that. Now i call this procedure from another thread and it works fine except when the thread calls the form.show() method it tries to show the form, but the form is nonresponsive and is locked up. I lock() the form object before its accessed, so i dont think contention is an issue. My debugging results show that all threads that enter this procedure, exit it successfully. However, any thread that is not the main thread that calls the form.show() method causes the form in question to be partially shown and immediatly become nonresponsive.