13.4 caused my BFGminer to immediately crash upon startup regardless of which version I used, and the problem to persist even if I tried to reinstall 13.1. As it turns out, it corrupts the OpenCL, and forced me
to find a pretty cumbersome solution* to the problem.

EDIT:

Fixed. I am leaving this here for those who end up having my issue.

-Uninstall all ATI software.
-Restart.
-Create a batch file with the following and run it:

@C:
@cd C:\Windows\System32
del SlotMaximizerAg.dll
del SlotMaximizerBe.dll
del amdocl64.dll
del OpenCL.dll
del OpenVideo64.dll
del OVDecode64.dll
@Cd C:\Windows\SysWOW64
del SlotMaximizerAg.dll
Del SlotMaximizerBe.dll
del amdocl.dll
del OpenCL.dll
del OpenVideo.dll
del OVDecode.dll
@rmdir C:\ProgramData\AMD\KDB /S /Q

-Reinstall ATI 13.1 drivers.