Plugging in more than one external hard drive freezes computer

I don't usually bother other people with computer problems as I just go through the standard trouble shoot steps (replacing hardware, drivers etc) But this one has me an my IT buddies confused.

I recently got my media PC working again after replacing motherboard, ram and cpu. (nice intel gigabyte motherboard now)

I have installed all the chipset ad motherboard updates.

The problem is that if I plug more than 1 external hard drive into the usb ports my mouse freezes and I get windows delay write errors. If I plug on one drive in (any of my 5 externals) then they work fine.
But just let me try plug another hard drive in or USB stick at the same time and boom (well not an actual boom)
If I unplug all the drives and replug my mouse back in then the mouse works again.

Do you think I have :
A) power issues - need new power supply
b) need to find even newer usb or motherboard drivers
c) need to re-install windows for the 6th time?