Personally, I think the problem is that the CF card is not properly formatted - but this is just a guess, not 'hard facts'.
If you have a laptop computer, it will probably have a PCMCIA slot in the side of it. Go to a computer store and buy a CF card PCMCIA adapter that fits into the PCMCIA slot and allows you to connect the CF card directly to your computer. These adapters are cheap, less than ₤10 before tax for sure.
Put the CF card in the adapter, and the adapter in the PCMCIA slot. If you are running Windows XP (home or pro), no drivers are needed, the computer will recognize it as removable media. Right-click on the icon representing the CF card, and select "format". De-select "quick format" in the next dialog - you want a full low level format, not a quick format. If you are offered a choice of which file system to use when formatting the CF card, choose FAT (file allocation table), not NTFS (NT file system).
Once you have done that, it will probably work fine. By the way, it takes about one-tenth the time to load a CF card with maps using the PCMCIA adapter than it does to load the same card with maps using the USB cable - so one of these little adapters should be considered 'standard equipment' if you own a 512 meg or larger CF card, and have a laptop.
When you want to load maps to the CF card, don't even bother connecting your GPSR to the computer. Just have the CF card plugged into the computer, press the little icon within MapSource that you use to download to the GPSR, and in the subsequent dialog that appears, push the button that says "find device". The MapSource application will find the CF card in the adapter - so download to it. When the download is done, just remove the CF card, and stuff it in your GPSR.
By the way - you might want to start this download just before you go to bed, and plan on removing the card in the morning. It can take a few hours to do, depending on the speed of your computer, and what OS you are using. But, with a 1 gig card, the only time you will ever have to load it is when new version of the cartography are released by Garmin.
PanEuropean
NB: You can only load a CF card to 90% of its stated capacity. For example, if you have a 1 gig (1024mb) card, you can only load '1024mb x 0.9' of maps - as indicated by MapSource - into your card. The computer needs the remaining 10% of the space to build directory information. This is the nature of removable media, not anything having to do with Garmin.
