Update on this.
Finally sorted the Intel Driver problem out on the laptop (used the Microsoft one from Windows Update WDDM 1.1 version).
Once this and the ICH8 and 82801/82802 PCI Bridge etc. were fixed build 7068 works fine now. Same with Wireless.
The Intel chipset seems to have been the problem. Don't know why but the MS stuff fixed it all. Now happily running build 7068 x-64 on the machine.
NOTE you have to do the update Manually -- from device manager etc. You can't do it via the normal Windows update program.
Cheers
jimbo