So i have had this black 8x since launch day. i got my first invalid sim msg on dec13, and second with in 24hrs of first. i contacted vzwsupport and winphonesupport via twitter. both units advised to pull and re-seat the sim card . ive done that and got a third error last tuesday. i was then further advised to reseat the sim again and also change the roaming toggle under the cellular setting.
well, i got my 4th invalid sim error this morning after booting it up from a manual over nite power off. happened with in 3 minutes and everytime has been, totally random.
Experienced this issue on the first 8x i received in November 2012 and on new one sent by verizon in May 2013. Since then, I have tried replacing the sim and later adding tape, neither have fixed this problem.