Fix: How to remove Trovigo.com, SearchProtect, restore Internet Options
Trovigo.com is an unwanted search engine hijacker that renders Internet Options of Windows / Internet Explorer inaccessible. To restore them on an older Windows XP installation, one way that I’ve found to work is to update Internet Explorer to a newer version, aka IE 8 (say via the embedded Windows Update facility or Microsoft Update website – http://update.microsoft.com)
The software is also probably related to a software (at least on the machine I was fixing) called "Search Protect", that is running a service and two other processes that one launches, that tries to stop you from killing it and from changing search engine option in the web browser. To remove that you can use Process Explorer from http://www.sysinternals.com:
Right-click the SearchProtect service and select Suspend (do the same for the two other processes it uses) to freeze it (breaks into the process with the debugger).
Right click the service node (that has the other two processes shown as children under it in the process tree) and select "Kill process tree".
Go to %ProgramFiles% (usually C:\Program Files) using Windows Explorer address bar (or type this in Start/Run… dialog and press OK) and remove the folder "SearchProtect"
Use free software like CCleaner (http://www.piriform.com) free edition (it has a tool to edit startup entries) or the really powerful Autoruns one to remove the now broken (since you deleted the software at step #3 references in various Windows settings that try to launch the SearchProtect software (Autoruns shows in yellow startup references to missing files, can right click and delete those entries).