Ghost Display: 'Generic non-PNP Display'

Question

Before I start talking about the problem I have Thinkpad T420s 4173-W1J (which has Intel HD + NVS4200) and I have never used it with any external displays prior to this issue:
A while ago I noticed a strange problem. If I let the computer enter sleep mode by itself (due to inactivity) and then woke it up, the built in display would be turned off and I had to use Fn+F7 and kind of work my way, blindly, to the right display output.
I figured this was because the Thinkpad thought there was a secondary display and sure enough the Device Manager and the screen-res settings in windows showed a 'Generic non-PNP Display'. I started to look around on the web for solutions as I wanted to bring this to an end asap.
-I started to uninstall drivers then reinstalling drivers. It didn't work!
-I tried uninstaling drivers, then installing the video drivers from Intel and Nvidia support sites. It didn't work!
Then I started to look at the hardware side of things...
-I plugged in my external display to the VGA and as I did so it replaced the non-PNP with PNP. I figured that there was something wrong with VGA port or one of the GPUs. This would probably suggest that the hardware thinks theres a display connected when there isn't. As such it cannot detect which display it is i.e. non-PNP. Then when I plug in an external display it finds a display on that same port, replacing the non-PNP display status.
-I read that this non-PNP phenomenon could be due to dust in the VGA. So I vacuumed it. It didn't help!
-I also read it could be due to electrical load on the port due to a faulty graphics unit. For this I need to send it in to get it fixed, but I did not give up yet...
-Lastly I heard it could be due to electricity caught up in one of the capacitators that the output used (or something like that). This was a thread about a similiar problem for a desktop and it was suggested that the person in the thread should disconnect his LCD from the PC and unplugg the powercords and let it rest for 5-10 min. I was desperate for a solution to my problem and so I figured I'd try something as similiar to this. I unplugged the power cord to my Thinkpad, removed the battery and waited 10 minutes. Sure enough when I booted up the 'Generic non-PNP Display' was gone!
I thought I had fixed it! I checked the Device manager several times that day and there was no ghost display visible. However, as I booted my Thinkpad the next morning, it was back... removing the battery and waiting 5 minutes fixes the issue as it did before. This is not a solution to the problem. I cannot remove the battery each night only to reseat it the next morning. Then I would never be able to use sleep mode.
I guess I should use my warranty to get my T420s fixed since I without doubt think this is a hardware issue. Does anyone have any other suggestions?
T420s 4173-W1J
i5-2520M // 8GB RAM // Intel 320s 160GB SSD // 1GB Nvidia N12P-NS2 // Intel 802.11agn // Bluetooth // 1Gb Ethernet // UltraNav Secure Chip // Fingerprint reader // Camera // Win7 Pro 64

Answer 1

I am too fond of my Samsung display so I wouldn't give up after you explained to me that I basically could end up with any of the other displays if I issued a repair.
So I kept on trying and figured out the following...
-Shutting down the computer, removing the battery, putting it back in a second later and booting 'fixes' the issue for the time being.
-Restarting the computer after the above is done, does not make the problem re-appear.
-However, shutting down the computer and booting it a second later does make the problem re-appear.
Now I know how to 'artificially' remove the problem and how to make it re-appear, which is good for testing purposes.
The following tests were made after making sure that the problem was existant in the previous boot...
-Booting with a VGA monitor connected finds the display (as it should). When disconnecting the monitor in windows it is not visible in anymore (as it should be). The ghost display does not appear in its place so this 'fixes' the problem until the Thinkpad is shut down and then started up again (without the monitor), at which point the problem has re-appeared.
-Entering any BIOS menu (F1, F8) before bootup without doing anything or changing any settings 'fixes' the problem until the next boot.
Strangely enough, what ended up fixing this permanently (won't know for sure until tomorrow morning) was a combination of doing the following...
-I pressed the Thinkvantage button. Went to the windows settings and pressed repair windows. After the files where loaded and it asked me to continue to choose a restore point I pressed cancel and rebooted. The problem is now non existant in windows. Before shutting down I turned off the 'Dynamic Brightness Control' in PowerManager. Now I can't reproduce the problem and I've even tried three times.
I don't know if it's the Magic Blue button or if it was the PowerManager settings (the latter being more plausible) but for now I am one happy fella.
A strange thing I noticed is that all the checkboxes for the 'Dynamic Brightness Controll' are still checked, even though the feature seem to be disabled since I the screen does not dim. I guess it's nothing to worry about...
EDIT: This is still not solved! Sometimes the ghost display is there, sometimes not...
T420s 4173-W1J
i5-2520M // 8GB RAM // Intel 320s 160GB SSD // 1GB Nvidia N12P-NS2 // Intel 802.11agn // Bluetooth // 1Gb Ethernet // UltraNav Secure Chip // Fingerprint reader // Camera // Win7 Pro 64