Wireless Xbox 360 problem

I bought an Xbox 360 wireless adapter for my basement setup to connect via an upstairs D-link.

http://www.amazon.com/Xbox-Wireless-Network-Adapter-MN740-360/dp/B00005QBX9/ref=pd_bbs_sr_2?ie=UTF8&s=videogames&qid=1226891030&sr=8-2

Everything worked after I told the 360 product which wireless signal to grab and what the WEP was.

The upstairs computer where the router is, was rebooted and it could no longer connect to the internet.  I unplugged the 360 adapter in the basement rebooted the upstairs computer and the upstairs computer worked again. 

Now in my basement I can connect to multiple nearby wireless signals with good signal strength, however when connected to the router upstairs, I am unable to ping a website despite being told it is CONNECTED with 4 bars signal.   ALL OTHER SIGNALS I connect to work normally, with the exception of the one upstairs.  What the heck did the 360 adapter change?  Or is it another issue altogether?

Thanks for any help.