Just a random thought here but is it at all possible you downloaded the wrong update? I was thinking you possibly applied the root download rather than the manual stock 2.2 by accident. Only reason I am thinking this is that many ppl have updated via the stock manual update with no issue & I know there were some wifi issues with some of the root versions. Was the update process more or less the same as when you did 2.1 a few months ago or was it different? If different, how? This is only a random thought and may be way off, but figured it was worth checking since you have tried several other fixes already. Another way to check is to look in your app drawer and see if you have a su (superuser) app. Personally I think this unlikely but again worth checking.
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