I have had an Ipad 2 for approx 6 months and recently had the documented problem of 'Invalid Sim' or 'No Sim Installed'
After reading around, I took it along to Apple who immediately issued a replacement. I asked if it'was a known problem and the girl said that it was.

OK - great so I have a new Ipad to setup.

Talking to a friend the other day , he too had this problem in the UK we chatted together and the thing which we both have in common is that we both use the smartcover.

It occurs to me that perhaps the magnets which affix the cover to the device are somehow damaging the signal slot.
One of the magnets is located directly on top of the sim card.
Anyone good any feedback on this ?
I don't think I want to have the same problem in another 6 months ( when the warranty is finished )