Hey Milton123, thanks for the reply, all my VMs have been created with the same PC, but the machine has been flattened several times since then. My colleague uses a copy of my main work VM and he has no such problems with his USB devices, but his host machine uses a newer chipset. I have not tried a driver update for my host machine yet, but I have removed version 9.0.2 and re-installed 9.0.0. I now have fully working VMs and all my USB devices work. The problem happens if VMware.exe is running, regardless of what state your VMs are in, running or powered down.
It's an odd problem, it makes me reluctant to try new products and updates from VMware, but I do have a workaround for now.