I've had that problem with my 8125 for a while
sorry man, as soon as I figure it out I will help you..
Other than that, the farthest I've gotten was downloading Magicdisc. You can make the .iso file a disk.. without having the disk.. does that make sence? So you can install it.. The only problem is that it installs TomTom home to your computer and not your ppc. I try installing maps onto my ppc from tomtom home but right in the middle of it it says my device has been disconnected.. And it HASN"T! so I'm in a bind.