Weird ongoing crashing, fatal error in main thread

[Silresa]

Having some weird crashing issues with a server - note that many players are NOT having it and some are, and it happens primarily with certain zones (usually the same ones for people who have the issue.)

Things I have tried:
Adjusting memory usage settings, texture quality, pixel shaders, texture streaming
Adjusted eqclient to have a normal ratio when playing windowed
Set exe to run in compatability mode, dpi scaling off, run as admin
Updated every redist I can find related to eq/eqemu recommended on the forums for eqlive and eqemu for c++ runtimes
Did the same for directx
Deleted eqclient.ini and started fresh
Grabbed a fresh uifiles folder from someone without a crashing client and overwrote mine (also redownloaded appropriate sarsexp and tried that)
I've updated video and sound drivers as well

I do run two boxes, not sure if that would cause it to screw up in this fashion, but many other players on the same server are doing the same (I also made a copy of my directory and run each instance from a different folder, just to be safe. )

I just double-crashed so it doesn't wanna crash now of course since I just relaunched my clients, but if the specific data in the "fatal error in main thread code" is useful I will be more than happy to post it in a follow-up.

Thanks!

There seems to be two parts to the error: Sometimes it hapens while in zone and I can just not click okay on the error and keep playing.. but any textures which haven't yet loaded will not load. It's just endless expanses of gray shapes and character models without textures.

The other part is it will crash when zoning (if I zone after ignoring a crash it was always 100% crash, leading me to believe it's pretty much the same thing.) This happens to a lot of people playing, but only some, despite having identical files/UIfiles/etc.

I'm really at a loss and would appreciate any help at all. The relevant part of the crash log seems to be a fatal error in main thread - and again some players get this same crash at the same zone almost always, others haven't had it happen even once. :( Logging back in and continuing is generally more or less fine, but zoning several times, especially into some zones, tends to make it happen.

Pretty sure it's the ROF2 client, for what that's worth.