Internet problems

I'm not too sure if this is the right forum, but I have two problems with my computer and internet. Atleast, two that I can remember.

1. For some reason my computer dosen't always load certain pages and i have to keep refreshing in order to get it to work.

2. Sometimes (mostly when i'm downloading files using BitComet) my computer just stops loading pages from the internet. I can't access any page and I have to restart my computer in order to use the internet again.

Soloutions please?
Thanks.