Bizarre Internet Connection - Anyone?

I have a strange set of circumstances surrounding my networking problem, and I didn't see anything close to this in the last 10 pages of posts, so forgive me if this has been answered somewhere else.

I'm working on a small lab for my job, where the ISP is a large organization that's giving us a little pocket of their connection out to the internet that's off the main backbone.

Now it's worked in the past with its current configuration, and has been more or less reliable. However, when it was first setup and now once again, its behaving very strangely.

Using Internet Explorer 7.0, the only browser allowed on the machines, I can visit Google.com and Niketalk.com, and apparently only those sites. I can enter in a search for Google and get a full set of results very quickly. However, when I try to click any of the results, it displays the message "Opening page" <insert page> in the status bar, but never actually loads the page, just hangs indefinitely.

I run an ipconfig /all, and everything looks normal. I have an IP assigned by DHCP, and the subnet masks and default gateways match up.

So I try to ping some sites, and get responses back from every site. I ping my NIC, my DNS servers, and other computers on the network. No problem! Quick replies from them all. So I try a tracert on one of the sites that won't load in IE, same deal. Gets there with no timeouts in a quick, timely manner.

To sum it up, my browser will only load a couple of select pages, and those pages are fully functional. Aside from those two pages, nothing else will load, but instead just hangs at opening. Never even errors out. From ipconfig's perspective, nothing is wrong. All addresses are as they should be, and everything is tracable and ping'able.

If anyone can offer any insight into this bizarre internet behavior, it would be much appreciated!

FYI, I do not know what kind of router it is, it's not even located in our building. I have drops coming from the ceiling that run to switches on the wall. I can't post the ipconfig screen from those computers, because this site won't load on those machines. I can, if someone deems it necessary, just jot the information down and post it here by re-typing it.