web components dissappearing

I have run into a problem where I work with a Web Form for a while and get it almost good to go only to find during a test that something has gone wrong (via an exception displayed in the browser). I return to the IDE and find that the web components have been removed from my form. Do you know what causes this problems and how I can avoid it? This has happened a few times and I am force to recreate my form. This only effects my presentation. Any help is appreciated.

Thanks,

I've seen some strange behaviour, but this isn't one of them.