Periodical creation of /dev/apmX entries

Hi,

does somebody know, why the current RELENG_7 tends to generate new
/dev/apmX entries every 45 seconds on my Dell Dimension 4600?

After a few hours there were around 900 /dev/apm entries, ranging from
/dev/apm to dev/apm898.

The kernel does not have device apm built in and dmesg does not reveal
anything as well.

# uname -a
FreeBSD medusa.sysfault.org 7.0-PRERELEASE FreeBSD 7.0-PRERELEASE #6: Mon Jan  7 23:10:13 CET 2008     root_at_medusa.sysfault.org:/usr/obj/usr/src/sys/MEDUSA  i386

Any hints on what could cause this behaviour are really appreciated.
If you need further system details, let me know.

Regards
Marcus