I had the same problem.  I returned my Simpletech CF, and picked up a 512mb Ridata CF from mypcmax.com ($153).  No problems since.  

Apparently the PicturePad has problems with a few CFs out there, or at least the Simpletech.

My new PicturePad is excruciatingly slow at downloading from a CF.


       I used the following equipment:
       -- Canon D60
       -- SimpleTech 512MB Type II CF
       -- Delkin 20GB PicturePad.

       I took the CF card with about 50MB worth of pictures, plugged it into the PicturePad and timed the download.
The download rate worked out to 2 to 2.5 MB per minute (yes, per minute).  There might be a slight difference depending upon whether the files were RAW (6 MB), Large JPEG/Fine (2.3MB), or Small JPEG/Fine (0.7 MB, but all were in that range.  That means it would take 200 to 250 minutes to copy a 512MB CF to the PicturePad.