could it be you guys have apps from extras devel and testing which are not fully compatible with the new firmware? i would suggest removing all apps/plugins which have not passed through extras testing. take note of all the apps you installed after the update (no doubt you've sucked the ovi store dry)
There's too many vairables to figure out what the problem is so just cut them out and put it back to known working apps. Even some apps that have passed through testing may need to be tweeked. there was nothing mentioned in the changelog about refresh rate on the gsm bands.