>>>Because this way I may hit the same problem I'm currently having with this class. However, I'm going to try it tomorrow, may be it would be enough.
>>
>>Just as you would do with editing and adding the PEMs one by one from the old class, you can do the same, just in reverse, with a copy where you would remove things one by one until you find out which one was the cause.
>
>It's not that simple as it sounds. Doing it in reverse way as you're suggesting will take much longer to find the problem comparing with my idea to start fresh.

Actually, few weeks ago someone here suggested a faster way: remove objects in groups, by class. First remove all the textboxes, then combos, etc. Also, you may comment out all the code and then uncomment gradually.

There's no sure-fire way to know... unless you could be more specific about the actual error.