After installing a fake certificate to install the video driver for Intel HD Graphics I've got troubles with the user accounts. When I start Windows it starts with the screen that the password is incorrect (I set it up previously to start directly without putting the password every time). then I realized that it says incorrect because this is not my user account. I switched and logged in and went to control panel user accounts and there is still only one user account...MINE. I don't know why it keeps starting with an other unexisting user account and I don't know how to recover the original certificate mentioned above. I tried backing up to a previous date and it's the same. Help

PS. The watermark "Test Mode Windows 8 Pro Build 9200" also appeared after installing the fake certificate