Which mods do you try to play? You have corrupted mach1.met file. If you adjusted it yourself then it's possible that you made a simple mistake where a single character is missing and then the game won't start.

I really recommend using a version control system like Git or Subversion. It helps you track your changes and it's then easy to spot errors or revert back to working settings after unsuccessful mass edit :).

To test & see if mods would work with this new version of the game, the only thing I did was change the amount of damage the reaper's plasma rifle inflicted. (From 3 to 99) With the new version I downloaded I have noticed that there is no "data" folder, only a "pdata" folder (which only has descriptions of missions). However, in the old modding tools folder there's one that says "data" which lists everything. (constructions, machines, weapons, etc) Weird...