how to REALLY get rid of "a program has corrupted your default search provider"

Modifying REGISTRY settings incorrectly can cause serious problems that may prevent your computer from booting properly. Modifications of these settings are at your own risk.

• Close all Internet Explorer windows
• Click the Start Orb
• Search regedit
• Click Continue on the User Account Control
• Navigate to HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\SearchScopes
• Right click the SearchScopes folder
• Click Export
• Give the backup a name and pick the location then click Save
• Right click the SearchScopes folder again
• Click Rename
• Add _OLD to SearchScopes (so that it reads SearchScopes_OLD)
• Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\SearchScopes
• Right click the SearchScopes folder
• Click Export
• Give the backup a name and pick the location then click Save
• Right click the SearchScopes folder again
• Click Rename
• Add _OLD to SearchScopes (so that it reads SearchScopes_OLD)
• Navigate to HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\User Preferences
• Right click the User Preferences folder
• Click Export
• Give the backup a name and pick the location then click Save
• Right click the User Preferences folder
• Click Delete
• Open Internet Explorer

This should force Internet Explorer to create new registry keys for both SearchScopes and the User Preferences. Sorry if you've already tried these, but for thoroughness wanted to make sure we covered them.