/ BLOG / Black Windows logon screen?

We had a good one at work the other day. One of our customer’s terminal servers, from their load balanced cluster, had run out of diskspace on C:\, due to a rogue update of some bespoke software and a lack of quotas. This is something which was missed from the config, but we or the customer never noticed, as we’re pretty good at monitoring this stuff and resolving the issue before it causes trouble. Sadly this happened so quickly that it avoided the monitoring in this instance.

To cut a long story short the disk space was regained, but any logon attempts to the terminal server yielded a completely black screen, with exception to the Microsoft logo. We figured it was a client side caching problem, but it was not so.

Turns out that when the disk space on the primary partition (C:) fills up the default colours can be overwritten, which results in the black logon screen.

KB906510 details the fix, but not so much that it’s caused by the disk space issue. If you’re looking for a quick fix to the default colours, then just save the following as a reg file and import it.

Windows Registry Editor Version 5.00

[HKEY_USERS\.DEFAULT\Control Panel\Colors]
"ActiveBorder"="212 208 200"
"ActiveTitle"="10 36 106"
"AppWorkSpace"="128 128 128"
"Background"="102 111 116"
"ButtonAlternateFace"="181 181 181"
"ButtonDkShadow"="64 64 64"
"ButtonFace"="212 208 200"
"ButtonHilight"="255 255 255"
"ButtonLight"="212 208 200"
"ButtonShadow"="128 128 128"
"ButtonText"="0 0 0"
"GradientActiveTitle"="166 202 240"
"GradientInactiveTitle"="192 192 192"
"GrayText"="128 128 128"
"Hilight"="10 36 106"
"HilightText"="255 255 255"
"HotTrackingColor"="0 0 128"
"InactiveBorder"="212 208 200"
"InactiveTitle"="128 128 128"
"InactiveTitleText"="212 208 200"
"InfoText"="0 0 0"
"InfoWindow"="255 255 225"
"Menu"="212 208 200"
"MenuText"="0 0 0"
"Scrollbar"="212 208 200"
"TitleText"="255 255 255"
"Window"="255 255 255"
"WindowFrame"="0 0 0"
"WindowText"="0 0 0"

Or if you don’t trust me just export HKU.DEFAULT\Control Panel\Colors from a “working” Windows server. The effects are instant.