wifi issues in ios5.1

Hi ,

I am having issues with wifi after ios5.1 update,

my home network i am using wpa2 security, it occasionally connects, some time it shows connecting (rotating circle) and shows a wrong subnet of 255.255.0.0 instead of 255.255.255.0 , this really surprises me , most of the time it says unable to connect , then i use forget the network option and reset the network settings create a new connection for the wifi , rarely it will again recognize, but it again disconnects when i am out of home. while i am on wi-fi network screen and "Ask to join Networks" is not slected , but still i could see many wifi network at my near by home showing up. this is also a bug.

Simillaly at my work occassioanlly i am having issues with wpa2 enterprise, but does not shows wrong subnet, if i try few times it connects.

i am having comcast at home using a old wireless router for wifi brought in 2007 d-link