usb devices not recognized after shutdown and restart

Archived from groups: microsoft.public.windowsxp.hardware (More info?)

I have a ugly customer (calling each four hours) - totally nerving !

Two usb devices (one US-Robotic USB-serial modem and one
ZyAir B220 (wlan usb-adapter) connected to an XP home client.

At the usb-connector there are also two usb-printers connected,
which are always be recognized.

My problem: The two added devices (modem, wlan) are not
recognized at startup.

- When I plug off the usb-cable after cold (!) start of each device
and replug the win xp will recognize the now hardware and everything
is working with this device fine (plugging off both devices and both
are working fine).

- When I connect to the modem and make the diagnose out
of system-console, the modem answers me with correct para-
meters, but it will not work due to error 678 (I only think this is
the correct number) - I am not at the cutomer - when plugging
off the modem and reconnect it via usb, all is working fine.

- When doing a warm start, all is working at startup.

I know about the correction og Microsoft bug 838989 (redetect
usb devices after reboot), but it was not me to install the computer.
Therfore I will install WinXP SP2, but I also expect that thit SP2
failed at installation before. I will download this SP2 and install
it again.

What can be the reason for this.
Tomorrow I have to go to my customer again (going to hell ...).

What's about calling Microsoft support, and so on ... ?

Thanks Harald