Having trouble viewing video online after defraging with norton utilities

This is the second time I have had problems after doing this. The first time I took my laptop in to find out what was wrong and they said there was a problem with norton utilitiess so they uninstalled it and it worked fine afterwards. I reinstalled utilities but my laptop was still slow so I defraged and optimized with utilities again thinking all was well and I have the same problem again. I uninstalled utilities myself to see if that would do it but it didn't.