Thanks. I found this too via Mr Google:
'Not to mention the fact that with wireless mice, the data rates with USB 3 can cause interference with 2.4GHz antennas commonly found in wireless mice (found this out first-hand with my logitech).'
I have now moved the receiver to one of the two 'main' USB ports and this appears to have resolved this issue. Should this not be part of the instructions as not everyone would know this?