I recently had a problem on my Macbook where Safari would stop working after a few minutes of connecting to the network, but other network applications, like Firefox, still worked. It was odd. Safari would just sit and hang.
After some research, what ended up working for me was to create a new network profile. Here are the steps to do that in Mac OSX (10.7.2).
1. Go to the Apple Menu in the upper left and choose
2. Click on the "Network" icon.
3. At the top select "Edit Locations..." from the Location drop down.
4. Click the plus sign to add a new location and name it something like "home" or "work." Then, click "Done."
5. That should be it. Safari should work now.