Sorry for the very long delay.... Had some coder's trying to get in....? Can you do a "scanreg/ restore" from a DOS boot to regain functionality?

Are your .gif files properly associated

Here is the advanced box and how it should look

If you do not know how to do the scanreg/restore Let me know and I will walk you through it

Could it be some mal-ware on youre pc? Can you post a hijackthis log? (see link below)

And if you have WinXP SP2 then i would un-install that pop-up blocker , the one in SP2 does its job perfect.