Vista - Help With IE8 search provider corrupt message

Today when I opened IE8 i keep getting a message saying "a program on your computer has corrupted your default search provider setting for internet explorer" I click ok and the manage add ons search providers pop up. even though I deleted yahoo search and have live serch as my default I keep getting the message. I even resetted IE8 and the message still pops up. any ideas on this?

1. Make sure IE 8 is closed then navigate to registry key: HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerUser Shell Folders
2. Add a new “Expandable String value” inside the above mentioned key with a value name of “AppData” and a value data of “%USERPROFILE%Application Data”.
3. Reopen IE 8 and see if you still get the error message.

I did a system restore which seems to have worked and the message hasnt appeared again. Can someone tell me what causes this though? And is it a serious problem to be concerned with?

Here is a good link with 2 answers to resolve this problem
Cute Auto Poster FAQ - My Internet Explorer search provided default is corrupted, please help me.