XP OEM shut down Problem

I installed XP Home on a Biostar M7VIG Pro / ATH 2100 CPU combo. After setup, validation and updates I discovered a problem with USB and also I got a" Its safe to turn off your computer" on shutdown error. I confirmed USB in the bios reinstalled XP from windows and searched MS knowledge base for answeres but nothing helped. I switched Hard drives and installed another OS. Same problem. I switched main boards to MSI MS 6390,same problem. The USB sort of works sometimes but seems like there is a conflict when it does, yet device manager says no. I had to call MS to reactivate last time and dont know how many times they will let me do that. Whats wrong and how can I fix it? The only thing common to all the variations is a Emachine USB card reader. I checked the pin out on the connector and its OK plus the reader sees SD cards without any problem. Its just the front and rear USB ports that dont work.