I think you need to sort out reception issues and wireless security (WPA etc).
Start by connecting the computer directly to the router by ethernet cable instead of wireless and see if problems go away then proceed as follows:http://www.tomshardware.com/forum/31382-43-find-security-password-wireless-router
You should also try to optimise your reception and avoid interference.
1) raise the router above furniture level
2) Experiment with channels (some will work better or worse depending on your environment)
3) If you can detect strong neighbouring wifi, use a channel 5 stops away from strongest.
4) Relocate cordless phone base or video sender etc.
5) Be prepared to move the computer (or at least turn it so your body is not between the router signal and the wireless adapter's antenna.