Green squares on lock screen after Windows 8.1 Update 1

Hey all,

I encountered something quite worrying today. I noticed that whenever I put my PC into Sleep Mode and waking it up afterwards, green squares would pop up on my Picture Password that I use to unlock my PC. These green squares ONLY pop up on the Picture Password and ONLY when waking up my PC from Sleep mode (see picture below). There are no squares on the picture password after a reboot. Browsing through pictures or gaming doesn't give these squares either.

I tried to change the picture password and I noticed that they also appear on others EXCEPT for black pictures.
Clicking on the green squares makes them disappear. I didn't install anything recently except for the Update 1 of Windows 8.1 although that was 4 days ago.

My specs: Windows 8.1 Pro Update 1 x64 with Media Centre, EVGA nVidia GTX 660Ti (not overclocked) with 334.89 WHQL driver, i5-3570K stock speed, 8 GB RAM and 1 TB Harddisk.

What are your thoughts about this guys? Could it really be my GPU giving up despite the problem being so limited to the Picture Password after sleep mode?? My PC is 1,5 years old.

Hope to hear some relieving answers and a possible solution for this..



Update: Just installed the 335.23 WHQL drivers but the problem is still there.

UPDATE: I just did a reformat and installed Windows 8 without updating to Windows 8.1 to test this. I noticed in this scenario that there are no green squares but small green pixels on the Picture Password (see here: [url]http://www.4shared.com/download/u98GC2vGce/20140414_011608.jpg?lgfp=3000 [/URL]). Unfortunately, Windows automatically installed the latest WHQL driver (335.23) so I'm not sure if any earlier drivers (before 334.89 WHQL) also caused this. Also, I'm not sure if these green pixels were there before the reformat and before installing Windows 8.1 Update 1 since they are hard to notice.

After updating to Windows 8.1 (that automatically installed Update 1 along with it) the green squares are back again.

Any conclusions regarding hardware problems or driver problems that could be drawn from this?

No one who could help me here?

As far as HW goes, symptoms like that are usually because of video memory.

Can this be fixed? Is there a diagnostic tool for testing video memory?

JohnnyGui said:

Can this be fixed? Is there a diagnostic tool for testing video memory?

Click to expand...

Try this program : Download Video Memory Stress Test - MajorGeeks

For some reason I'm getting this error when clicking the start button to start the test:

Changing video mode to 640x480x16...ERROR (Code: -2)
[23-4-2014 19:18:07] Test started for "NVIDIA GeForce GTX 660 Ti"...
Trying 32bpp RGB:888 mode...OK
PATTERN NOT FOUND
Trying 32bpp BGR:888 mode...NOT SUPPORTED (Code: 80004001)
NO PASS COMPLETED

Also, I read here VMT.exe test results and questions(Video Memory Test) - EVGA Forums that it is not advisable to use outdated programs to test hardware. I can't find any other reliable recent VRAM testing programs.

It's working here even at 1440 x 768 res. Did you try Cuda setting ?

Choosing Cuda setting gives me this:

Changing video mode to 640x480x16...ERROR (Code: -2)
[24-4-2014 12:38:10] Test started for "GeForce GTX 660 Ti"...
Preparing CUDA...Module load error: 300
NO PASS COMPLETED

I just noticed while trying to change the resolution to 640x480x16 manually, that there is no such option in the settings. The minimum resolution is 1024x768. Could this be the problem?

I kind of narrowed down the problem. The problem seems to occur on specific resolutions. So far I have seen it occur on 1920x1080 (my standard resolution), 1024 x 768, 1440x900 and 1600x1024. It doesn't appear when choosing 1680x1050 or 1600x900.