Compaq Armada e500 - Notebook PC Quick Reference Manual page 188

Problem
External device
connected to a USB
connector does not
work
External device
connected to USB
connector does not
work during startup
(before Windows 95
loads)
External devices in
lower tiers do not
work
IMPORTANT: External USB keyboards will not function until the
operating system has been booted.
16-40 Troubleshooting
Solving USB Problems
Possible Cause
The operating system
limits external devices
connected by USB to
two tiers which can
include no more than
two hubs on the first
tier and no more than
one keyboard and
one pointing device
on the first or second
tier.
During startup, only
two tiers are
supported by the USB
connector. These tiers
can include no more
than two hubs on the
first tier and no more
than one keyboard
and one pointing
device on the first or
second tier.
An unpowered hub is
connected to another
unpowered hub.
Solution
Reduce the number of
connected external USB
devices to no more than
two hubs on the first tier,
and no more than one
keyboard and one
pointing device on the
first or second tier.
Use the external device
only after Windows 95,
Windows 98, or
Windows 2000
Professional has loaded.
Reduce the number of
connected external USB
devices to no more than
two hubs on the first tier,
and no more than one
keyboard and one
pointing device on the
first or second tier.
Use only powered hubs.
Make sure that all
unpowered hubs are
immediately preceded
by powered hubs in the
USB chain.