KVM question, somewhat OT

This isn't exactly a Linux question, but I thought someone might be able to
help me. I have two Linux boxes and two Windows boxes connected on a
four-port Linksys KVM switch. The problem is that one is a new notebook
with no PS/2 connectors; it has USB only. I got a cheap (ca. $30)
USB-to-PS/2 adapter, which has two identical PS/2 ports on it. If I plug in
a keyboard to this, either directly or through the switch, it works fine.
But the PS/2 mouse (actually a trackball but I think the protocols are the
same) works only directly, not through the switch. I was wondering, is this
due to the failure of the USB converter to recognize the switch's mouse
emulation port as a mouse? I thought maybe there was some difference
between the mouse and keyboard cable pinouts, and that I could maybe clip a
pin on the mouse's switchbox cable so it couldn't accidentally appear to be
another keyboard. But the pinouts appear to be identical. Has anybody else
dealt with this problem? Of course, I can use two mice (actually two
trackballs) but that defeats the convenience of the KVM switch.

Thanks,
Vaughn Treude
Nakota Software, Inc.