Bought a 64GB 3G unit about 2 weeks ago. When I got it home and turned it on for the first time, I received an error message saying No SIM Card Found and, where the AT&T bars would normally appear in the upper left hand corner, it simply said No SIM. I popped the SIM card out and put it back in and the bars reappeared. Didn't think much of it. I wasn't traveling for a while so I turned off Cellular Data and didn't purchase a monthly 3G data package - connected through WiFi at work and home. I had to go out of town on Thursday for the weekend so I activated 3G service for the first time Friday morning. Process worked flawlessly and I was surfing the web for several hours. But then, all of a sudden, the same No SIM error message appeared and I couldn't connect. I took the SIM card out and put back in several times. Every now and again, it would recognize the SIM, start working for a little while but would then crap out again. I called Apple Support yesterday afternoon and explained the problem. They searched the knowledge base and had no reports of such a thing occurring with an iPad. There were some reports of this happening with the iPhone so they read me those suggestions (i.e. power on/off, remove and reinsert sim while powered down, etc.). I tried all of that but would still only get periodic connections. So the logical next step was to replace the SIM. Went over to an AT&T store late yesterday afternoon and popped in a new micro SIM. It was the first time they had this type of request but had just received a shipment of micro SIMs from Apple to support the iPad. The new SIM worked at the store and for a while when I got back to my relative's house so I thought I was home free. But then the No SIM error message appeared again and it became apparent that this is a hardware issue that just hasn't been reported enough to make Apple's knowledge database yet. By this time it was after hours so I filled out the online support request for a call back this morning. I played around with the SIM for a while longer last night and realized that it would recognize the SIM pretty much every time when I would pop it out completely and then reinsert very slowly. It worked most of last night and this morning but by early afternoon the error message came back. Called Apple back this afternoon and they scheduled a Genius Bar appointment for me on Monday to get my iPad replaced. Just wanted to know if anyone has ever heard of anything like this with the iPad. Did a bunch of searches in this forum and on Google for No SIM error messages but not a single hit came back. Guess I'm the lucky fool that got the only iPad in the country with this type of hardware failure. Not a big deal but kind of an annoyance - especially while being out of town this weekend without access to WiFi.