стоит Debian testing (wheezy)
apcupsd 3.14.10-1

apcupsd.conf:
....
UPSCABLE usb
UPSTYPE usb
DEVICE
....

в один прекрасный момент в логи посыпались:
2012-03-15 18:24:11 +0200  apcupsd 3.14.10 (13 September 2011) debian startup succeeded
2012-03-15 18:31:00 +0200  Communications with UPS restored.
2012-03-15 18:31:43 +0200  Communications with UPS restored.
2012-03-15 18:31:53 +0200  Communications with UPS restored.
2012-03-15 18:32:01 +0200  Communications with UPS restored.
2012-03-15 18:32:09 +0200  Communications with UPS restored.
2012-03-15 18:32:18 +0200  Communications with UPS restored.
2012-03-15 18:32:26 +0200  Communications with UPS restored.
2012-03-15 18:32:38 +0200  Communications with UPS restored.
2012-03-15 18:32:47 +0200  Communications with UPS restored.
2012-03-15 18:32:54 +0200  Communications with UPS restored.
2012-03-15 18:33:04 +0200  Communications with UPS restored.
2012-03-15 18:33:24 +0200  Communications with UPS restored.

удалил apcupsd, поставил заново, перегрузился, теперь в логах:
2012-04-01 11:56:04 +0300  apcupsd FATAL ERROR in linux-usb.c at line 609
Cannot find UPS device --
For a link to detailed USB trouble shooting information,
please see <http://www.apcupsd.com/support.html>.
2012-04-01 11:56:04 +0300  apcupsd error shutdown completed

root@serv:/var/log# lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 008 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 002: ID 051d:0002 American Power Conversion Uninterruptible Power Supply

подскажите, плиз, куда хоть копать ?