Periodic problems with MBP internet connectivity

I've noticed a couple of times now since owning my MBP a strange occurrence where although my MBP is connected just fine to my wireless network, my internet acts up on me. What I mean is this, there might be a brief time where I get server timeout errors anytime I try to access ANY website, but that usually only lasts for a couple minutes. Then I try going to a site like google and it works just fine and searches without a problem and a few other sites load up without a problem, but other sites take an extremely long time to load if at all. I tried restarting the Mac, shutting down the Mac, opening and closing the browser and none of it worked. I also noticed that any e-mails that were in my outbox were stuck there and not going through. So now after almost 4 hours of the computer being off it all seems to be working again. I noticed this once before when I was running Parallels and I had no problems visiting websites in Parallels while OSX browsing was next to impossible. I was thinking it might be something to do with the airport wireless, but then you would think browsing the web in Parallels wouldn't work just like in OSX at the same time. I haven't yet ruled out my router or ISP, but I'm just curious if anybody thinks there could be some sort of problem with the laptop itself. I've only had this happen to me a couple of times so maybe it's just a fluke thing.