Something abnormal to my pc

I recently downloaded a program on my system and was working fine until about an hour. Afterwards it crashed all of a sudden. I restarted in the "last known good configuration" which worked and everything was fine for several hours. The next morning I started my pc and everything seemed to be fine until I clicked on IE icon to open a browser. A blank page came up with "Microsoft Internet Explorer" along with another blank page over the first one. I found very difficult to close the second page.

I still think there is something abnormal to my pc. How can I resolve it?

What was the program that you have installed? Also which operating system are you using?

I am having Genuine Windows XP Pro and I have downloaded and installed some tweaks for it.

Go to Programs-> Accessories-> System tools-> System restore.

Hope this will help you