If I try to copy a file from my memory card(8GB SDHC) to my PC using ActiveSync or SOTI Pocket Commander I get the following message:

Cannot convert file "xxxxxxxxxxxxxxxxx"

A device attached to the system is not functioning.

I can copy the file back and forth between my phone's built-in memory and memory card just fine using Resco Explorer, and I can copy the file from my phone's built-in memory to my computer using ActiveSync or SOTI without any error. The only problem seems to be with copying to my computer from my memory card, though I do remember intermittent problems trying to download directly to the memory card over a data session.