I've looked through the forums and haven't seen this yet, so here goes.
After the OTA ICS update, my Rezound was behaving more strangely than usual, so I followed the great instructions supplied by TisMyDroid: Getting the most success upgrading to ICS from GB. I backed up everything with My Backup, did the FDR, and then restored everything. I am now re-calibrating my battery per the instructions, which requires that the phone is turned off while charging (for the first two cycles). I do this overnight.
The problem is that for the last two mornings, when I turn my phone on after charging, I immediately get a message that I do not have a SIM card in the phone. This message disappears after about 5 seconds. The call function works fine.
I'll mention that I have always had trouble with the phone connecting to either 3G or 4G, but after the fdr, it's been worse, as has been my wireless connection. I can't figure out why this would just happen after an fdr, but I'm not a techie, so someone else may have some ideas. In the meantime, is the best thing to do to pull the SIM card and then remount it?