Try turning off selinux at boottime;
When the grub splash screen is displayed press any key
Select the Linux boot choice and press the 'e' key
Select the kernel line and press the 'e' key again
At the end of the line add a space followed by selinux=0
When done press the 'Enter' key followed by the 'b' key
If you can log on then you need to adjust your selinux security policy or disable selinux permanently.