Hi,

I've now had the opportunity to try out a new Serial to USB-cable
(this one: http://astronomiser.co.uk/converters.htm#serusb), and it
has solved all my worries.

That is, Guide still struggle to command my telescope directly (a
Celestron compatible SynScan AZ), but through the use of ASCOM,
commaning the scopes and slewing Guide worked flawlessly.

When selecting the "NexStar" option in Guide, however, it first
reported through a message box that "NexStar GPS, 5i/8i/11i or
Compustar detected" (or something along those lines), but refused to
slew Guide. Whenever I tried to slew Guide, it later complained about
"Could not open COM port", but it happy slewed the telescope. But when
it didn't work both ways it was a bit awkward.

But since ASCOM worked so well, I'm all set.

So for others out there struggling, getting a proper cable may well be
all it takes.

Arild :)