it might just be summat trying to start up. check your start menu and remove anything that is not essential/required at start up.
also have clear out. remove any programs that you never use now. tidy up the hdd. have a general spring clean.
you might have a virus on it. check out the other threads re hijack this and other tools.
the best solution is a format and a clean install. the thing will wizz along then. gauranteed.
remember,, backup any files that are required, first!