wifi connection stops responding (only on open browser tabs)

I have a 13" 2.3GH i5 Macbook pro that I puchased about a month ago.

When surfing on my wifi, after being on any site for a while, that site will stop responding. Any other tabs I have open will no longer respond either...the pages just endlessly try to return whatever page I tried to click to. The only way I can get the browser to start returning pages again is if I do one of two things:

1-open a new tab and go to any website (websites not previously opened in the session always work fine.) After that, i can go back to the original tab and click on anything and it returns right away.
2-Or, if I turn my airport off and on again, the tabs that stopped working will start responding again just as they had been. (without restarting the browser)

I'm using chrome, but it happens in firefox too. This only happens on my home network...everything seems fine on other networks. I'm not convinced it's my network, though, because my old macbook, my dell and a friend's laptop always work perfectly on the same wifi, so its got to be something with this computer.

any suggestions?

Sounds like your router and modem needs a reboot or possibly a replacement.
What model and brand router and modem also how old are they?