MacBook running slow and safari doesn't load

Hi
I'm having a problem with my MacBook, it's running very slowly when you open some applications. Safari opens and loads a little bit then the rainbow wheel comes up and the MacBook freezes and only occasionally if you wait long enough can you force quit it and then that freezes. Also the software updater also freezes yet word, PowerPoint, excel and firefox all still work fine. I've tried uninstalling and reinstalling safari but same problem still happens.
Please help me.

only safari? have you tried other browsers like chrome, firefox?
by the way what version is your safari? 4.0.1 or 5.0.2 or ......?

Try reseting Safari in Safari>Reset Safari>Reset
Hopefully that will work.

Hi i tried restarting but it did nothing it wouldn't even finish the restart. Even tried deleting the app using appdelete and reinstalling but also did not work. Its safari 5.0.3 and tried updating but get error code -1001 which is something to do with the internet connection i believe. Firefox works fine its just safari.