Vista - Ethernet connection problems

I'm having trouble getting my laptop to connect to the internet at work. I've connected with no problems previously, but the other day it stopped working. It now just says that it has limited or no connectivity. There's another computer connected to the same router that works just fine, and I have tried using different plugins on the router as well as different cables. It's not my ethernet jack, because I can still use it to connect to my router at home.

The problem began after changing the key used for encryption on the wireless router we use at home. However, this change hasn't affected my ability to connect to the internet anywhere else (school, a friend's, the local coffee shop). I've checked my drivers, and they are all current.

Check the encryption is the same on the Office modem as it may be locked into lets say wep when it should be wpa or it may not be detecting it.