My laptop, using XP, connects perfectly to my wireless router, and others. Recently I tried to connect to a wireless router at a friend's house for the first time. After going through a normal start-up the laptop seemd to recognise the router but then went into re-start. I tried several times and this happened every time. With the router switched off the laptop started up as normal. As soon as the router was switched on the laptop shut down for a re-start. The router works perfectly well with the friend's PC. Any ideas?