Need your help before I decide to return my P67A UD7 to the retailer.

I'm having very strange problems.

Let me explain, I have A Coolermaster Stacker and connected the usbF1 and 2
located on de bottom of the mb to the cables of my case.
When I than place the Logitech Unifier in one the the usb slots my KB and mouse
work, but during post Delete Key does not work, so I used a cables kb to enter
the Bios.
When I place the receiver in the back USB 2/3.0 slots I'm able to use the
wireless kb Delete key.

Yesterday all of a sudden I received a short flash msg. stating somethin like
"usb hub peak voltage error etc" I only have two usb connections 1 for my Printer 2 for the Logitech Receiver.

Also my Asus D1 pci sound card located in the bottom slot, is sometimes not
recognised (so no sound)

I did a clean Windows 7 64 bits install and meanwhile flashed to F6 also my
Sapphire hd5770 is now giving a kind off coil whine sound, previously on
my P55 ud6 these problems were not present.

So concluding do I have a buggy moederboard or are their any options /
suggestions which I could test prior to returning the bord tomorrow.

I think this is my 8th Gigabyte mb in 10 years, but haven't encountered
so many problems before.

thanks for your appreciated feedback.