I am using using Ubuntu 14.04 as my regular OS, but from time to time I have to switch to Windows at my work. It has now happened at least twice, that after spending a few hours in Windows and coming back to Ubuntu I was unable to connect to the same wireless router.
Last time when I tried to solve it I noticed that Windows was having trouble connect as well after a few times of switching back and forth between boots. At first the windows diagnostic utility could solve it, but after a while it could not. I also reinstalled the windows driver for the network card. My last attempt that seemed to solve it, was that I switched the router from automatic channel to a different specific channel, so in the end I thought it has nothing to do with the dualboot setup. Naturally, I tried this again (set it to a different channel) but it didn't help. Both the current and the previous channel is unoccupied by other wifis (at least there are non I can see).
The network is configured to be DCHP, with reserved IP-s for the computers we regularly use here. Nobody else has a connection problem. Nor do I have trouble connecting to the wifi at home.
Does anybody have any idea what could be the cause of this?