first are you using Internet explorer as your browser if so is it IE7? do you have firefox browser on it? if not go download firefox and see if you continue to have those same page display problems, when trying to use firefox. So it can be determined if this is a browser problem.
http://www.mozilla.com/en-US/firefox/

Here is a link that might be useful: Firefox

If using Firefox as Ravencajun suggests fails to show improvement try this
click Start
click Run
type ipconfig /release
click OK or hit Enter

A black box appears then disappears.

Repeat the above but now type ipconfig /renew
hit Enter or click OK

Any improvement?

Can you list what was done when the computer went back to Toshiba? The more you tell us the better chance of a fix. Why did they decide not to replace the computer?

I have a Toshiba and haven't a problem with it. I haven't used it a lot, bought it for travel.

I am currently using a Toshiba and have had several before. I dont think its the laptop, I beleive its probably a setting which is not made. Have you been keeping up to all your Vista updates and do you have an up to date antivirus program on there?? Do you run ocassional antispyware cleanups???

I have EI7 on it, and I have AVG free antivirus that is up to date. I have only used the laptop maybe 20 times because of all the trouble I have with it.
Toshiba had to put a new modem in it right off the bat. It wouldn't connect at all when I first got it. Then the other two times I sent it back was because of what I mentioned above and they sent it back saying it was fine but they did reinstall everything for the third time!
They told me they don't replace them even though I had only had it a month or so and only had it on maybe 6 times. Just their policy and I told them what I thought about their policy too!

berk how do you connect to the internet? cable, dial-up, fios, dsl tell us that and also do you have a router connected to the computer? Give us as much info as to what you are using for connection including who your provider is, Verizon, Comcast, etc...

Next where did you purchase the laptop from you may have recourse in returning it through them rather than dealing with toshiba, did you purchase it with a credit card?

I use Dial Up with a local place in town here called Powrup. I never have trouble on my regular computer, which I am on now.
I bought the laptop at Walmart on Dec. 8th. 2007, so I don't have a warrenty let on it now.
I even wrote to a head guy at the Toshiba company and they did noting to help me only said they don't exchange laptops. I informed them I wuld never buy another Toshiba product for sure!
My connection speed is any where from 21-24Kbps, the computer I am on now works great, never a problem. The laptop gives me enough problems for the both of them!

ok try getting the firefox browser and use that to see if you can get to webpages.
that will let us know some info we need.

you can download firefox to your regular pc and burn the exe to disc or flash drive and then put it on the laptop if you need to do it that way.

Also try this to see if you may have a connection problem. Go to Start> connect to> all connections> hilight your connection> on left column click repair this connection.

oh you have Vista those directions at the end on how to find the connections are for xp but it may be the same for Vista not sure, someone with Vista might let us know, I do not have a Vista system here to look and see. If it is the same go ahead and try a connection repair.
I just happened across this article and in the replies there are numerous with toshiba laptops having this problem so it is sounding like it could be an issue in some models.
Repairing your internet connection with Diagnose and Repair

My Toshiba laptop has a mind of it's own. TOUCHY! This can get frustrating. I have connection problems on/off as well. Today I was fighting with it rebooted and all was well. I have noticed and don't know why - when the windows update icon appears in the system tray I will have connection problems till I update or disable the update. I use the back botton/refresh often. Shutting everything down for a period of time I will not connect till my router is reset. How are you set up? Do you use a router? Can you hardwire the laptop with a cat 5 cable and see what happens?

Sounds like a classic connection issue to me, not the computer. Have you tried different dialup numbers? Checked firewall settings? Definitely put in a decent browser. Opera, Kmeleon, Firefox or something. Can you access email? Have you changed phone cords? Tried a different phone jack? Tried it at a different location? Checked for driver updates? Windows Updates?

Well, I got my laptop out yesterday and other then running the windows update I did nothing to it. It stayed connected all day and I didn't have any trouble with it at all???
It worked great before and after the windows update. Strange, and that was the best it has worked since I bought it.
I can't send mail on it threw outlook but can recive mail. I have a google mailbox that I use when I am on it then.
Unreal how good it worked for me yesterday and I am afraid to turn it on today , lol.

that has to be a bad setting in your outlook account causing the mail problem try going into your account settings and make sure you have the info there put in properly for your incoming and outgoing server info from your email client.
I prefer using webmal these days anyway and if I do use an email program I use thunderbird by mozilla rather than outlook it is so much easier and better in my opinion.
you can get thunderbird from the mozilla link along with firefox which you never did mention if you tried??