My girlfriend has a linksys wireless B router. She uses a Macbook with wireless. Her roommate has a PC connected to the router via Ethernet. For a year or more now, everything has worked properly.
All of a sudden the router starts dropping the internet connection. Either for her, for her roommate, or for both of them. She connected her laptop directly to the modem and couldn't get internet but her roomate could when they connected to the modem directly to their PC. On my advice, she left the modem unplugged for 15 minutes then reconnected her Macbook directly to the modem. The internet worked for her.
With that tested, I figured it was the router. She goes out and buys a new Linksys Wireless G router. With the same setup as before (Macbook wirelessly, PC wired) the network drops out for both of them at the same time.
I'm inclined to tell her to go buy a different brand of router, but could it be a problem with the modem communicating with the router? Just a thought. Remember everything was OK with the wireless B router for years. The same issues are continuing with the Wireless G router. It could be crappy old Linksys (although I have been having a hell of a time with my 2 day old Airport Extreme).
Thanks