Hi there, try turning off or disabling your antivirus before launching your infinitymu client, also use mu.exe,
Most of the time some files in the infinitymu client are being consider as a virus by anti viruses,
Instead of updating your client, just download a new installer of the infinitymu client and install it,
For a fresh copy of the client delete your old infinitymu folder, don't forget to turn off your antivirus before installing the IMU client, try it sir.