Need to find reason for USB I/O errors [on hold]

I have a program written in Python 2.7 and wxPython 2.8 under Mint 13. One of the modules pulls data off a number of USB devices for subsequent analysis. Everything works fine with Dell laptops but when installed on the HP 255 G1 ~40% of them report USB I/O errors (all ports are USB 2.0). The errors are random and may not occur but the next time occur with 50% of the devices.

What I hope to do is get an indication of what is happening to cause these issues. My USB experience is very limited but I have considerable experience with modem communications.