USB Mouse sticks at bottom

[Jens Rehsack]

Hi all,

I have a problem with my FreeBSD 7.2-STABLE. My mouse tends to stick
at the bottom of the screen several hours after I've turned on my
machine.
The mouse is an USB mouse attached via a KVM switch.

Some historic:
After I've first installed the switch at the end of May 2009,
everything was fine. After an update (IIRC in August), the mouse first
time walks to the bottom and sticks there a few weeks later (6-10).
This frequency kept until the last update a few days ago:
> FreeBSD waldorf.muppets.liwing.de 7.2-STABLE FreeBSD 7.2-STABLE #0: Tue Jan 12 07:48:01 UTC 2010     root at waldorf.muppets.liwing.de:/usr/obj/usr/src/sys/WALDORF  amd64
Since that update, I can work for a few hours, after that the mouse
begins walking to the bottom and stays there.
When I switch to another machine running Windows/NetBSD/OpenSolaris
and switch back, I can use the mouse "normal" for 1-5 minutes, than it
walks down to the bottom again.

I called the technical support of the KVM switch - and they told me,
that the known reason for this is a power save mode of the OS.
That sounds plausible to me, since I knew that there were some merges
from the 8.0 USB-Stack to 7.2-STABLE and I've seen similar behaviour
on an Ubuntu Karmic installation (but neither NetBSD-CURRENT,
OpenSolaris nor Windows).

Now my question: how can I "debug" this issue (maybe get the time and
the event causing the mouse getting down) or how I could prevent that
behaviour (if anyone guess a reason or can confirm the statement from
the tech support)?

Thanks in advance,
Jens