Follow these steps
1: (while everything is at stock, so stock rom, stock driver) i execute this command first (as admin)
bcdedit /set nointegritychecks on
2: I reboot to safe mode(Hold Shift while clicking reboot) and i replace that atikmdag.sys file.
3: I reboot back into windows with that replaced atikmdag file. Windows should load perfectly, same for your drivers.
4: I flash my rom (command line atiflash, also as admin)
5: I reboot with signature checks disabled (also holding left shift while hitting the reboot button), you can do this in the next screen after you clicked reboot while holding left shift. You'll get a menu and you just do this. (same applies for Safe mode)
Troubleshoot > Advanced options > Startup Settings and click Restart
6: Everything should look perfectly fine when rebooted (i do not get the "test mode" message in the lower right corner. It just works

)
Ps.

More than 12hrs rock solid.
Greetings