To run MTA do next. 
Right click on MTA/properties/compatibility 
now set compatibility mode to windows XP SP 3 and privilege level: Run this program as an administrator. 
Do that with GTA also. 
Run MTA and it should be fine. 
Also try setting DEP(Data Execution Prevention) and set:Turn DEP for all programs and services except those i select. 
Click add and find MTA and GTA and add them. 
After doing this MTA should work fine.