USB hotplugging does not work on all machines anymore

[Markus Huber]

Just realised a weird behaviour. My desktop does not recognise:

- my USB scanner
- my USB connected external IDE hd-case

# lsusb
Bus 003 Device 001: ID 0000:0000
Bus 002 Device 001: ID 0000:0000

Bus 001 is not shown anymore, the query is blocked. So is hwbrowser and 
system-network-configuration (sic!).

The IDE-drive plugged in or the scanner on power even blocks booting 
into FC3.

And I cannot find any - at least to me - relevant information in the logs.

dmseg shows that:

# dmesg | grep "usb" usbcore: registered new driver usbfs
usbcore: registered new driver hub
usbcore: registered new driver hiddev
usbcore: registered new driver usbhid
drivers/usb/input/hid-core.c: v2.0:USB HID core driver
usb 1-4: new high speed USB device using ehci_hcd and address 2

On the contrary: on my notebook (a HP zd7000) everything works fine 
(same and latest patchlevel on both machines).

Does anybody experience the same strange behaviour or know a solution or 
workaround?

-- 
Regards
Markus Huber