Mouse turns on computer

[mato]

Hi all
For some reason, since about a week ago, my computer has been turning on when a button on the mouse is pressed (from a shut down, not standby). I can't find anywhere in the BIOS to turn this off, there is only a WAKE FROM KEYBOARD option which is disabled anyway.
Mouse is Deathadder and Mobo is Z77-3DH
Anyone know how to disable this?
Cheers

 

[mato]

Have tried updating the firmware an also de-selecting that option in the mouse's power management, but neither of those worked.

After some quick diagnostics, it appears there are only a couple of USB ports which it does this in. Just tried all of them and it only seems to be happening in some slots and not others...