Wireless problems using time capsule

Hi all!
I just got a time capsule and seemed to get it set up with no problems. However, now it only intermittently lets me open certain web pages (doesn't seem to be any rhyme or reason as to which ones it won't open) and it won't let me send e-mail. I can receive it just fine but it wants me to use a different outgoing mail server than the one I have in my settings.
When I try to go to a web page, it acts like it's starting to load, but then just gets hung up. Sometimes if I refresh the page it works, but mostly not. If I then try to go back to the same website later, it works.
Please help!!!! I have had my MacBook for over a year and I have never had these kinds of problems with wireless before and it works fine when I bypass the time capsule and just plug the ethernet cable straight into the computer from the cable modem.

Thanks!!!!