Hi glad you sorted it out any way. Just are you sure it was to do with the front USB connection ?
Thing is I have the same problem as do a lot of other Win 7 users plus I have the same rig almost as you x64 Win 7, CPU & Motherboard most importantly.
To get around it like other people with the same trouble I altered the power options of all power modes now to 'never' put the computer to sleep.
When the computer goes to sleep it won't wake & freezes. I have to power down the PC then power it back on leave it for about 5 to 8 minutes & it then eventually wakes.
Someone said it was down to the graphics drivers
but since you have Nvidia & I have an AMD/ATI card I doubt it very much.
Problem itself has to be down to the Motherboard (or its BIOS) & Win 7 x64. & would think it would be ironed out before long at either end by an windows update or ASRock BIOS flash.
Many people seem to have the problem on varying machines even manufactured of the shelf machines by the likes of dell etc.