If your school can get it and you can't it's probably a DNS issue, or, if you're running windows, a strange activex control is taking over your browser. Try checking your HOSTS file too, and look for any so-called plugins that could have snuck their way into your system that shouldn't be there.
I've ran into situations where a self installing browser object (activex control) in internet explorer would cause me to have strange redirects and loading behavior awhile back. When I investigated and found it, I removed it from the system and set the things it changed back to their defaults (i.e. search pages, etc...). Very annoying stuff.
Other situations involve a HOSTS file that something created on your system that blocks or redirects things to other sites. Also somewhat annoying as some programs are clever enough to change the location and name of the HOSTS file as well.
Last but not least, check what processes your system is running. On windows XP the only process that your really *need* to run is explorer. It's safe to blow away all the other processes under your user name. Then start up software that you intend to run. Things like IM clients, etc... Look at the process list. Figure out what should be there and what shouldn't. It's easy to tell when you have a program running that shouldn't be running.