got the same problem. i was trying to run my old installation, which was running fine on windows 8. since i updated to windows 8.1 it stopped working, compatibility mode doesn't work either. i reinstalled the game, and my mods, still no cigar. i reinstalled again, and tried running vanilla tdu which astonishingly DID work, but i quit after i was in the main menu. after i installed the carpack (which includes patch 1.66A) it was dead again.
EDIT: I SOLVED IT USING CLEAN BOOT, WHICH ISN'T SAFE MODE.
Followed this guide https://support.microsoft.com/en-us/kb/929135 which i can't post as a link for some annoying ominous reason.....
so thanks utnugp