Did you format your card on a Mac or a PC?
If you did it on a Mac, the Mac puts hidden resource files on the CF card in addition to the actual data files and folders.
The Radio which is running Windows CE then tries to read the resource files (.DS files). This can cause the radio to "hang" as it goes through all of the resource files before it finds the valid data files.
There is a Mac application called
Blue harvest that will remove these pesky files.
If you formated the card on a PC, it should pretty much be a 1:1 copy. Make sure your file names are not too long.