Most likely you have downloaded some spyware or something similar. If you can access the internet and download files, download Firefox from http://www.mozilla.com/firefox. Then download the following files and run them to remove the spyware.
http://www.microsoft.com/athome/security/spyware/software/default.mspx
http://www.download.com/Spybot-Search-Destroy/3000-8022_4-10401314.html?tag=lst-0-1
http://toolbar.yahoo.com/
http://www.download.com/Ad-Aware-SE-Personal-Edition/3000-8022_4-10045910.html?part=dl-ad-aware&subj=dl&tag=top5
If this doesn't work, you may have a virus. Download the following program and run it in boot mode or run a virus scan through your anti-virus provider.
http://www.avast.com
If all else fails, download this program.
http://www.majorgeeks.com/download3155.html
Please be advised DO NOT DELETE the results. First post them on the sites forums and let someone help you sort the results to find out which ones are threats and which ones aren't
If all of the above fails, revert back to IE6 or just continue using Firefox. God Bless and Jesus Saves.