You could try using it on the Win7 32bit PC anyway? Also you say you're using the latest drivers - have you tired using older driver versions? A BIOS upgrade for your motherboard maybe worth a shot
personally i wouldnt go with a bios upgrade
I suspect its the drivers. Essentially the program freezes, even after a task manager close down? I suspect its not releasing the drivers.
Does the driver start as a service? type services.msc if its in there stop/start the service. If i am right you only get the ability to use it again when you reboot right?
The issue is a bad driver, I am sure of it
I could be wrong, but im postive its not a motherboard bios issue, and as a rule i always flash a bios any bios as a last resort anyway!