Note that many websites have their own advertising, unrelated to adware.
AutoSearch is an IE Browser Helper Object that hijacks address-bar searches. It knows about some of the other prevalent search-hijackers ? IGetNet, CommonName and NewDotNet ? and will steal back any address bar searches they take over.
Any address bar search you do is sent to a single page at www.tunders.com (which includes only static adverts, no search results).
Open a DOS command prompt window (from Start->Programs->Accessories) and enter the following commands:
regsvr32 /u msinfosys.dll
You should now be able to delete the 'msinfosys.dll' file in your System folder (inside the Windows folder; called 'System32' on Windows NT/2000/XP).
It is believed that AutoSearch is installed with or by Wink/ASWnk ? check your system for this parasite.