KVM switch and wheel mouse

Hrm, I have quite an odd problem with my KVM switch: I run a wheel mouse under linux that I have mapped via xmodmap that doesn't function once I switch to another computer and back via KVM. My mouse wheel works fine in linux, however, once I switch to another work station on my kvm hub and back to the linux workstation the wheel mouse refuses to work. I'm totally boggled as to why.
I'm using a logitech mouseman ps2 wireless mouse, any ideas? Thanks.