Quoting Mike Miller <mbmiller at taxa.epi.umn.edu>:

<snip>
> I guess that is a KVM.  Three earlier posts before this one mentioned KVMs
> that also did not require rebooting.  Maybe I don't get this.  The whole
> point of the KVM is that you can switch without rebooting.
</snip>

That is the point of a KVM. The reality is that some are more stable 
than others, the less stable ones will occasionally "lose" the mouse 
leaving you to need to reboot the box on that port in order for it to 
"find" the mouse again.