Browser issues in OS X 10.5.8...

Just bought this 13 inch macbook pro a couple days ago. I'm loving it so far, but I'm also having issues. At times, i'll be browsing the internet when either I'll go from one page to another, or just opening up a browser, and I wont be able to connect to any pages... It just sits and loads and loads. However, other applications running off the internet in the background run fine: uTorrent, Software Update, Messenger, etc etc. The only fix it would seem, is to restart the computer... Anyone have any ideas for fixes or anything?

I'm using Firefox primarily

However, I also have these issues in Safari