I'm experiencing this too, and I also disabled most addons/plugins to no avail. I set up the crash dump generator, but nothing was generated in 3 different crashes (crashes to desktop?). I also have a two-monitor setup, and from what I can tell, it only started happening after the September version update. My laptop, with the same plugins/addons (but only one monitor), seems to have no problems.
Lastly, for me, it only seems to happen when casting a spell or using an ability - never while idle/chatting/running around.
Probably won't help, but here's my error message:
Problem signature:
Problem Event Name:BEX
Application Name:pol.exe
Application Version:1.18.13.0
Application Timestamp:4e3bcddc
Fault Module Name:Hook.dll
Fault Module Version:4.2.8.1
Fault Module Timestamp:53f99f66
Exception Offset:0010b6bd
Exception Code:c0000417
Exception Data:00000000
OS Version:6.1.7601.2.1.0.256.48
Locale ID:1033
Additional Information 1:3fb6
Additional Information 2:3fb641e0463a7c373e768cd82c07cfce
Additional Information 3:2ac8
Additional Information 4:2ac84cf1d9c884d015add715035fa4d9
Update: after reading the last few pages of the Windower thread in FFXIAH, I disabled timers, and it's been stable since - it used to crash promptly (5-30mins) when repeatedly using a quick spell to trigger the crash. I'll update if I do crash, but I've got two instances of FFXI doing this and one of them would've definitely crashed by now.