asterisk users - Dec 2006 - Can zaptel freak out if you configure 2 trunks but use only one?

I am using Asterisk 1.2.13 with Zaptel 1.2.11, I used to have an old PBX 
connected to one port and the PRI connected to the other.

I'm having serious stability issues with Asterisk on a box that has been 
rock solid previously.

The old PBX died two months ago so one port on the TE210P is now unused 
but still configured. Also I'm afraid I have upgraded from Asterisk 
1.2.9.1 and the old zaptel version because of the security flaws.

I'm now puzzled why Asterisk is being unstable.

I do a nightly restart because Asterisk is extremely slow in trying to 
resolve failed dns lookups for providers.

Often Asterisk will keep running or restart properly but on the console I 
can see it restarting / restarting the B-channels really slow (normally to 
restart all B channels takes max 1 second) i can really see it restarting 
one channel in about one second, and some channels are skipped.

It also happens that Asterisk refuses to start at all.

A reboot seems the only solution to the problem.

Could it be that the configured (but unused) trunk is causing me problems, 
buffer overruns or anything similar?  Or is this an issue with more recent 
zaptel and asterisk configs?

Thanks all!!