TL has apparently not the rights to change config files. Have you tried to run the game as administrator?

I'll give that a shot, thanks.

...didn't work. I must be the only one experiencing this. I can't get higher res than 1024 p.

Hello,
I use Windows 7 64 bits and had the same problem. Here is what I did: opened properties of the launching .exe and, checked Run as administrator, checked Compatibility with Windows XP SP3. I also changed my desktop resolution to max (1920 * 1200) because an official answer on Runic Games forum mentioned it in 2009 and that they would fix it in a future patch (but obviously didn't yet), then I could change the game resolution to 1600*100 or 1920 *1200 and checked Antialias and the game kept it. You can also try first to change the desktop resolution, maybe it'll work without changing the .exe.

There's an issue with dual monitors. If you have 2 monitors for some reason it wont go aboe 1024. Took me ages to figure this out. Unpluged my second monitor and it worked fine again

See Runic Official forum: http://forums.runicgames.com/viewtopic.php?f=6&t=685

That6 dosent really answer the question or resolve the issues, northing more than the dev's confirming the resolutions they use and that windowed mode is available. Nothing on dual monitor useage