Before reinstalling the 2.2 upgrade, I'd go into both wifi and network settings and have a careful look to see if everything remains as it was prior to the upgrade.
I'd even take the trouble to go into the application manager and clear all cache and data and defaults on wifi and network and everything related, reboot and then reconfigure, just to start fresh.
Then, if no joy, consider a reinstall. If you do the reinstall first, you may just import the problems to the new installation.