Disconnects since upgrade to 1.2

I have a 3 asterisk servers, one on static IP and the other two dynamic IPs which register to it using IAX. I had no real problems until I upgraded all three to 1.2. Now one of the two dynamic IP servers is dropping IAX calls several times a day. Each time it happens, /var/log/asterisk/messages shows messages like this right at the time the call drops:

app_dial.c: Unable to create channel of type ‘Zap’ (cause 17 - User busy)

and I’m also seeing message such as this in the log throughout the day but not at the same time the calls drop:

chan_iax2.c: chan_iax2: ast_sched_runq ran 11924 scheduled tasks all at once

The other dynamic IP machine also has similar “ast_sched” log entries but it is not dropping calls.

When I upgraded to 1.2, I made no changes other than commenting out two lines containing “chan_modem.so” in modules.conf

I’m not sure what to try, other than rolling back to 1.0.9. Any thoughts would be appreciated.

DB

Just a bit more info - at the * console interface of the offending server I’m seeing stuff like:

Nov 22 16:55:23 WARNING[20934]: chan_iax2.c:7971 network_thread: chan_iax2: ast_sched_runq ran 56 scheduled tasks all at once
Nov 22 16:55:23 WARNING[20934]: chan_iax2.c:7971 network_thread: chan_iax2: ast_sched_runq ran 125 scheduled tasks all at once
Nov 22 16:55:23 WARNING[20934]: chan_iax2.c:7971 network_thread: chan_iax2: ast_sched_runq ran 124 scheduled tasks all at once
Nov 22 16:55:23 WARNING[20934]: chan_iax2.c:7971 network_thread: chan_iax2: ast_sched_runq ran 3813 scheduled tasks all at onc

This doesn’t look like a good sign. Does anyone have a clue what could be causing this? I think this must me related to the disconnects but I’m not certain. I’d rather find the cause than just give up and roll back to 1.0.9