I use regular Linux text console a lot. And I switch between X server and the text console a lot. Sometimes the process caused complete lockup (no console working). After such crash I used to find my log partition full. 'daemon log' full of 'acpid: can't accept client: Too many open files', there was also a lot of acpi related messages in Xorg.0.log file.

Today I finally found out what is going on: each time I switch from the text console to X11 the Xserver opens another connection to acpid:

[root@jajo ~]# lsof -c acpid | grep -c socket
8

 -- switched two times between X11 and text console --

[root@jajo ~]# tail -n 4 /var/log/daemon 
Aug 21 14:45:37 jajo acpid: client connected from 7041[0:1000]
Aug 21 14:45:37 jajo acpid: 1 client rule loaded
Aug 21 14:45:41 jajo acpid: client connected from 7041[0:1000]
Aug 21 14:45:41 jajo acpid: 1 client rule loaded
[root@jajo ~]# lsof -c acpid | grep -c socket
10

Eventually acpid will stop accepting connections, the logs grow and the system locks up.

A simple workaround is to restart acpid from time to time, when in the text console.