Sorry this took so long…
So far, we’ve had two resolutions to this issue.
The first involved having our electricians come in and check all of the distribution panels - several of them were incorrectly wired, which was resulting in instability at the desktop. This did not affect the servers, however, and did not contribute to the locking up issue we were seeing, but having clean power made a tremendous difference in calls dropping at the desktop. Note that there were extensive tests required for line noise, etc…not just making sure hot and neutral weren’t swapped.
The second involved updating to the 1.2.x branch - so far, on three production boxes, we’ve had zero issues with 14 days of uptime on two of them. The third was done Tuesday, and the fourth box just was finished today. So, half our servers are on 1.2, the other half on 1.0.7.
The bulk of the issues we see are on the older boxes, so I have to say that our stability issues were caused by running the older Asterisk and/or Zaptel versions. We also have a dialer box running Vicidial that was updated to 1.2 a few weeks ago, and it has been running much better than previously.
I don’t know what more I could add, other than simply updating to 1.2, making a few minor modifications to the modules.conf and musiconhold.cog fixed our problems. We get several warnings due to our dialplan being slightly out of date (deprecated commands, etc) but those will be cleared up in the coming weeks, once all of our servers are running 1.2.
I will try to check in on this post should anyone have any further questions about our experience.
Thanks to everyone who helped out.