You know the thing that comes down when you type a letter in the Google or any other thing, like you type 't' and you see the column coming down that shows everything you have searched that started with that leeter, what is that called. How do you earse that? I know what your thinking, and no I don't have anything to hide

It's called Internet History

In Internet Explorer:
Tools > Internet Options > Delete History, Cookies and Temp files.

In Firefox 1.5:
Tools > Clear Private Data or Ctrl + Shift + Del

I think what dimitri06 wants to prevent is the "auto complete" feature.

To stop the auto complete go to internet options hit the content tab and hit the auto complete button and uncheck all the boxes. Hit OK and OK in the internet options window and your problem is solved.

Hope this helps.