My suggestion, which is rather extreme, is to do a reinstall of the factory image and see if that fixes things. I wasn't sure if your reference to starting for the third time meant you already tried that or are just on your third machine.
My T43 was buggy (crashes, BSODs, shutdown errors etc.) out of the box and eventually I sent for an EZServ box to send the *****Expletives removed by Moderator***** thing back but decided to try the reinstall, just in case. I was also careful to install apps and hardware piece by piece, restarting each time to check everything still worked. I had no problems at all after that.
I still have the EZServ box too. Not sure what to do with it