I have one of the last systems using a CD rather than a DVD.
Upgraded the disc to 2004-2005 version last year which seems to have an aversion to motorways.
Set it for Warwick from Swansea and it wanted me to go up through mid Wales, around the North of Birmingham and back down again. Crazy.
Set it in Burscough to go to Birmingham and it sent me through Widnes. When ignored and I went onto M6 it kept telling me to reroute back through Widnes.
I have checked for settings that could be making it do this like "avoid motorway" but there do not seem to be any such options.
Any ideas on why it is doing this. I now tend to route by map and switch on when I am a few miles from my destination

Not too sure in the GS matey, in my IS200 there is an option to have motorways as a priority route even toll roads and mines a 2000 cd rom based system? it does sound like the road priority is turned off on yours though but not sure what menus you have on yours compared to mine so that it can be turned on?