Blocked wireless

[#1]

my wireless stopped working, so i decided to reset my router and see if it would work then. Weird thing was when i asked my housemate to try and connect to her wireless, then for some reason the router restarted itself, and this happened when she went upstairs twice. Could it be possible that she had blocked my wireless as well as restarting the router? 

[#2]

If you have 2 wireless routers in one house then they are likely to interfere with each other if they are on the same channel they will be worse. Reseting your router would set it back to the default channel which may now be the same as the one upstairs.
Download netstumbler free from http://www.netstumbler.com/ and check you are both not on the same channel. 

[#3]

...or adjacent channels. If they're on the same channel they should at least be able to share.
Also check you haven't given them the same SSID, unless you're using some kind of roaming mode (advanced stuff).