CallerID Suddenly Stops Working

[chashock]

I'm encountering a strange issue I'm hoping someone can shed some light on or assist me with my troubleshooting tree.

 

I'm running IVM 4.20 on WinXP SP3, with a Zoom V.92 PCI Voice FAXModem (which is listed as a modem that works with this software).

 

My users wish to have all calls with blocked CID sent to a special mailbox to deal with apart from the rest of their voicemails. The system worked beautifully until the middle of the day 9 days ago. I cannot isolate that anything materially changed, but after about mid-day on the 19th, every call that comes in is shown as having blocked caller id. I've tested several times without blocking my CID to be sure that all the calls really aren't blocked, and my calls show up as blocked. I've pushed the number of rings before answer up to 3, knowing that CID info comes in between ring 1 and 2, but that didn't help, and I had it at 2 rings before when it worked.

 

I'm in the process of doing a system restore to the 18th, to see if that makes any difference at all, but I doubt it will. Has anyone else had issues with Zoom modems suddenly losing their ability to report CID information correctly?