I know this problem (including the launcher crashes after defragging). Two things helped in my case. First I cleaned my notebook, it got really hot sometimes and then I got freezes. Your hardware seems to be fine, so maybe you can skip that one. But if you want to check, for me CPUID HWMonitor was very helpful to determine the problem.
Second and important one. I made a clean install. Tried one game vanilla and then installed Aslains step by step, most important mods first and wait what happened, then next. I could install everything I wanted, never got issues again. I run a very bad system (i5, GeForce GT520M (mehhh...), 6GM RAM and Windows 7). Now I got with standard graphics and medium settings 50-70 fps, still use WoT Tweaker. Maybe I'll try improved graphics after the next patch.
Remembered a third thing right now, there was a problem with the language file that caused the launcher crashes some time ago. Maybe you can try to choose a different language in the launcher first, just change, wait for new settings, change it back and maybe everything is peachy (didn't help with the fps problem).
Good luck!