What I noticed on my N900, is that if I don't use WifiSwitcher, and restart my router, it works as normal again, all the time. But when I use WifiSwitcher, it can't connect to my wireless connection. So, until it's fixed, uninstall it or not, try to restart your router and see what happens? For me, just restarting the router fixed my problem.

/Trancedancer