Thank you everyone who gave your opinions and solutions. Thanks to all of you I think I figured it out, for now.
I managed to install the newest BIOS, version F6, which says that it fixes compatibility issues with USB's. I also uninstalled and reinstalled the USB drivers, and made Windows always give power to them, so they never go to "sleep".
This far, it hasn't lost connection for over 18 hours. If it loses connection again, I'll let you know.
Thank you Andre and Alex for your tremendous help.
Best Regards
Sts013