A12 BIOS for Studio Xps 1640 has a bug.

I want to get the word out that I have experienced a bug after downloading the A12 BIOS, and have reverted to the A11 BIOS since.  The problem occurs when Windows Power Options attempts to dim or turn off the display. The display quickly dims to black and then remains off despite any effort to turn it back on.  The only way to fix the problem is to shut down and restart the computer.  I have reproduced this issue many times.

(To avoid a hard shut down, you can either plug in a monitor or possibly press Win+Right_Arrow+Enter). 

I have a Studio Xps 1640 with a 1920x1080 RGBLED screen.  If anyone else experiences the same issue, please let me know.

(As a side note, the issue is most common if you you set the Windows Power Options to dim AND turn off the screen after the same amount of time, for example 1 minute for each opperation.)