Screen keeps dimming on E6420

Anyone else experience this?

I have an E6420 with HD+ (1600x900) LCD, about a year old, that dims intermitttenly, usually after a few minutes of being turned on. Once that happens, nothing I do will change the screen brightness except going into calibration menu, which seems to reset the screen. Output to an external monitor exhibits same behavior, which seems to me indicate it's not a hardware issue. Two weeks ago, screen would not turn on, contacted Dell, they wanted me to send the unit in for repair. When I received the unit, it seemed fine. Three days ago, however, I experienced the same symptom, except in reverse; the screen got real bright and I couldn't dim it until going into calibration.

When I contacted Dell, they told me the connector to the LCD was disconnected and all they did was to re-connect the cable. Can the loose connector explain the behavior I was experiencing? And what about what happened yesterday? Hopefully that was just an one-time thing but my instinct tells me otherwise.

On a side note, although I can't see how it's related, computer seemed really laggy and it locked up a few times and I had to shut down cold. I have a 256GB SSD and I had never experienced this laptop freezing like that. Then I got an error saying the Office validation key was invalid and no matter what I did I couldn't resolve the error nor re-install the suite. Re-installing Windows 7 and rolling it back a few months seems to have resolved all the issues.

Thanks for reading this; any comments would be appreciated.

 

how much space is left on the SSD ?

I wonder if you maybe having some disk issues - try running diagnostics on the disk drive.

it may all be related as far as these issues above, I am kinda torn between a hardware issue or a software issue on this one.

 

Plenty, it has 175GB free.

 

the loose cable would account for the LCD display, but having the same problem on an external display tells me the issue is with the GPU.

So update your drivers, maybe your BIOS and see what happens,

IF it still does it I would be asking Dell to replace the GPU / mainboard.

 

Thanks, rep'd!

After re-installing W7, I updated all the drivers and I believe there was a BIOS uodate as well. So far, I haven't experienced the problem again, but definitely will have them replace the main board if it reoccurs.