It's lucky I haven't got any hair or I'd be pulling it out! It's your fault, Adam, as I thought I'd try the "slew to zenith" thingy. I get an "ASCOM driver error invalid response" message every time I try.
I re-installed the ASCOM drivers - twice - and tried re-starting everything but to no avail. The little I've found about this message indicates I should load the latest drivers, which I did. This appears to be the same problem the guy had in the video I watched, so maybe he was right?
Anyone got any ideas?