If you have a suspicion that your IE has been compromised by adware there are many products to help you clean this rubbish software from your computer. For Windows XP I'd first try Ad-Aware from Lavasoft.

Ad-Aware @ Lavasoft - The Original Anti-Spyware Company
First choose English as the language.

For those who wonder, first look at:
Free software downloads and software reviews - CNET Download.com for Ad-Aware and look at the number of downloads.
Of those Adware removers which work without going down to the raw O/S (for those serious rootkit infections) IMHO this is a good one.

Btw. If you are a commercial company, please do pay for the software. It helps all of us beat this malware.