First suggestion.... do a battery pull on your 8900... if that does not work, pull the plug on your wireless router.... for both of these battery pull or pull the plug, you should leave the power off for about 20 seconds to be sure everything is reset properly... then put the battery back in or plug it back in... give that a try and let us know if it works after that.
I just loaded 5.0 and did a reboot after... still not working...
Sorry... I mean sorry about your upgrading to OS 5.0... you need to go the BETA forum for those answers... I've heard nothing but problems from people that have upgraded to OS 5.0.