I don't remember the exact steps I did to create the crashes (appcrash) that occurred whenever I tried to "Restart" the Guild mission or Quit to main menu.
I was having that crashing issue today (even though I swear I had fixed it yesterday)... so tried tinkering with the cam_mod.ini more to no avail, and the screen resolution in cam.cfg. Reinstalled TFix a couple times. In the end, I got it all working. No need to read more, if you're okay with just knowing I am up and running okay.
My troubleshooting observations:
I eventually figured out I could "Restart" okay from an old saved game I had on the 'Assassins' level, but not from my 'Guild' level saved game that I had been trying the past couple days. Maybe the Guild saved game was corrupted somehow? I could load it and play it, but the torches weren't dimming and the game kept crashing when Restarting it. (The Guild was my farthest progress in the game, so that's why I kept trying to load and test torches and restarts from there.) After re-loading my Assassin's saved game and re-finishing that level, I made a new saved game on Guild. That seems to have fixed the problem. All attempts to "Restart" from Guild work fine now, torches dim, the sky is t2skies, so all seems to be well now!
One other variable that may have been causing crash problems before is a screen resolution out-of-sync somewhere? Maybe? Not sure. I had had 1920x1200 for quite a while, maybe from DDFix days? But when I was having framerate issues with the HD Mod the other day, I tried changing the resolution in-game to a lower one, to see if that would improve the framerate. It didn't. But I remember it was quite a short list of available screen resolutions to choose from and my 1920x1200 was not on the list, so I feared changing it in the first place, wondering how hard it would be to get back to my 1920x1200; I changed it anyways. Ever since then, the screen resolution for the game has been something less than 1920x1200 (which I hated, of course). Thinking there might be a disconnect in screen resolutions somewhere between files (or with my monitor's outside-of-game setting) causing the crashes, I edited cam.cfg today to make it say 1920x1200, thinking the in-game menu still didn't have that option listed. When I booted up the game and looked at the video options, however, I was surprised to see TFix added a long list of resolutions, with the 1920x1200x32 option as one of them. I'm pretty sure 1920x1200 was already highlighted because I specified it in cam.cfg, but I re-clicked it and hit Done anyways. Maybe that helped fixed some of the crash issues? It's hard to tell... My 'corrupt' Guild saved game still crashes even with the 1920x1200 resolution, but I'm now able to Quit to the main menu from that saved game (which is one place it would crash before), and can also start a new game (which was also crashing before). Since I have no need to ever load the 'corrupt' Guild saved game again, I'm not worried anymore; and I'll just overwrite it someday with a new save.
All's well that ends well...
If you're curious, voodoo47, here's some background...
In case you were curious, I did not do a "clean" install of TFix, in the classic sense of the term "clean." (Meaning: I wasn't working from a fresh Thief Gold install.) I had installed Thief Gold two or three years ago, and had probably loaded DDFix and maybe other patches at some point over the years, including the HD Mod very recently. As you remember, my problems began with the HD Mod giving me a poor framerate; so I wanted it gone. Since the first page of the TFix thread said that in order to uninstall the HD Mod I could just "repatch with TFix, and delete the hdmod folder when done," I tried that. In the end, that worked, as per the above info I shared. I never had to re-install Thief Gold, thankfully... and I'm pretty sure you weren't saying I'd need to do that anyways. Plus, since you indicated I could maybe just rename my HD Mod folder, I tried that, too. (That was actually the very first thing I tried.) So, I never tried a TFix install on a 'totally clean' Thief install.
As I recall, the following steps are what I did the past few days. I tried testing the game after each step... looking for torches to properly dim, enhanced textures, and t2skies, where appropriate. It's hard to remember the exact chain of events, so I would just take this with a grain of salt. It's probably not worth trying to recreate the steps on your end because my memory may not be that good here and things may be so convoluted...
1) Renamed 'HD Mod' folder.
2) I think torches weren't dimming after that, so I downloaded and installed TFix. Might have downloaded EP2.crf and put it in my Thief folder per the directions at this point, too.
3) Torches still weren't dimming, and I think this is where I first noticed crashes occurring upon "Restarts" and "Quits" because I started to do that after reading you have to restart the level to get the torches dimming. So, I deleted the HD Mod folder entirely as my next step in my path of troubleshooting, even though I figured it wouldn't make any difference since I had already renamed it. Issues still not fixed, of course.
4) I probably re-installed TFix again at this point, but was still seeing problems afterward. I think the crashing issues were temporarily resolved, so I could restart the Guild mission and see that the torches were dimming okay. (Note: The crashes came back earlier today in full force, though, for whatever reason -- even though I don't think I had changed anything between yesterday and today.)
5) Regardless, I still wasn't seeing enhanced textures yet, so this is about the time I started tweaking the cam_mod.ini file and plopping EP2.crf in different places than what was recommended; trying to figure out how to properly reference EP2.crf and t2skies since those weren't working either. That's when I posted above, asking for info on how to decipher mod_path.
Sorry for the wall of blue. I guess spoiler tags don't collapse text here like they do on some other forums.