Connection issues in Windows 7 (Minecraft/nplay/utorrent)

Do you have any custom software firewalls going on?

If you're absolutely sure that there has been no change on your network then may be worth going into control panel, further into Windows Firewall then on the left you will have "Allow a Program or feature through Windows Firewall"

There will be a button near the bottom that says "Allow another program" - it will appear in the list, feel free to tick all boxes beside it and try again.

What is your Java version? Which browser are you using?

Haha, welp - going with the information here I'm stumped without being hands on. Hopefully someone else may have had a similar issue and be able to assist you here.

May be worth asking another student to test minecraft classic or BeGone on their rig on the same network

Some extra things to test would be another browser, grit your teeth and try internet explorer - check addons within Chrome and Firefox, check if there are any updates pending for these browsers, try any other connection to compare to