You can turn off the auto fill form in:
Internet Explorer 6.0
Tools (Extra) - Internet Options - Advanced tab - Surfing (Browsing) - 'In line Auto fill'. Disable it. (This has been mostly translated from a localized version.)
Or go to Start - Settings - Configuration - Internet Options - Advanced Tab - Surfing (Browsing) - 'In Line Auto fill'
Deleting your History may also do the same. Considering that you only cleared the cache and cookies.