When I set up our wireless router, I initially set it up as an unsecured network and restricted access to certain MAC addresses. This worked fine but when we had visitors who wanted to use our wireless connection, it was a bit of a pain to allow access to their laptop. So I changed the router's configuration so it used WPA security and it all seemed to be working fine.
But then a couple of things happened which I didn't realise were related to this seemingly simple change I'd made. First, the wireless connection would stop working every few hours. This affected any computer connected to the network and would typically last a few minutes and then everything would be fine again. This was particularly annoying when I was connected to somebody's VPN and would have to re-establish a connection. The second problem was my Vista PC started to lock up completely. This was less frequent, about once a day.
I put the first problem down to the number of wireless networks in close proximity to our house. I guessed that they were just interfering with each other and causing the connection to drop every so often. Either that or our router was just getting on a bit. Then the other day I thought I'd give Vista's wireless diagnostics a spin and it told me the wireless security key was incorrect. What the...? This kicked my befuddled brain into action and realised these connection problems had started at the same time as the switch to WPA. So I switched back to an insecure network and lo and behold, the wireless connection is working a treat. Not only that but I haven't (fingers crossed) had a Vista freeze since the switch back.
So, if you're having wireless troubles, consider switching to an insecure network. I guess it may well be specific to my router but it may just work. Yeh, hackers can probably read my email, but frankly I hope they have more interesting things to do with their time.