wireless internet access limited to google...

Hi,

I've recently started having problems with my wireless internet connection :-( When I use my laptop (vista 32 bit) to connect wirelessly, I'm only able to access a handful of certain webpages such as google and wikipedia. I've cleared the cache numerous times, suggesting that I'm actually on the internet, and am able to freely browse each website, but if I attempt to connect to any other webpage, my web browsers (both IE and safari) tell me that there's no connection.

It's not a problem with the router, because I can access the internet perfectly both through local area connection and wirelessly on my mobile, so I'm left to conclude that my dell is playing up. I've tried to use Dell Support Centre to get technical support from them, but the program keeps telling me that I'm not connected to the internet, even when I'm using a cable (I guess that's another problem all together...) and I've used system restore, but that's not made any difference. This is the latest from a long list of numerous wireless connection problems, but while the other times I'd be able to sort it out by tinkering with the settings, I've had no success this time, and I'm at a loss and feeling fed up...

I'd appreciate any advice.