OK, did a full uninstall of the Altair Drivers and Reg entries, rebooted, reinstalled so I know that I have the very latest drivers installed.
Rebooted PC, checked USB3 connection and Lead, all fine. Checked USB root and Hub drivers, all fine.
Connected to SGPro, tried running 60 x 5m Dark Frames with a 20 sec delay between each sub to allow for downloading.
Got to 6 Darks taken - SGPro just stopped… it finally timed out and paused the sequence itself, had to manually start the sequence and its taking Darks again. Lets see how long before it tumbles again.
This time it got as far as 34 out of 60 darks and again stopped and had to be manually resumed.