Sounds like you might have a virus. Try restarting your computer in safe mode. This is how you do it:
1) click on start
2) select the option like you're going to turn your computer off, but select "restart". This restarts Windows w/out turning your computer completely off.
3) as soon as the screen goes black, start hitting your F8 key repeatedly (about once per second) till you get a screen that has what looks like a lot of technical info on it (the F8 key is on a row of keys labeled F1-F12 above all the other keys on your keyboard).
4) find the option that says "safe mode with networking", select (highlight) it & hit enter on your keyboard.
Your computer will boot back up in safe mode. If a window comes up telling you you're running in safe mode & asks if you want to continue, click yes or ok. Any text will be really big & the screen will be in black & white....you'll also see the words "safe mode" in all 4 corners.
Now try to open your internet explorer. If you can get onto internet explorer, try to surf a couple of websites. If it's acting normally & will let you surf, then chances are you have a virus. I'd suggest taking your computer to someone you know/trust (who won't charge you an arm & a leg hopefully...lol) and have them clean it up/out.
The reason for safe mode is 'cause it "bypasses" any viruses and/or any anti-spyware/anti-virus/firewalls you might not have disabled. Also, make sure you have IE 7, not IE 8~IE8 is still in the beta phase & has some bugs that need to be worked out. Hope this helps & good luck!