It's not a bug. It' a feature!

June 24, 2011 6:55 AM

Weird laptop computer behavior. Was it really User Account Controls?

So, it's a Dell Inspiron, x-64, Windows Vista Home Premium. A couple years old, no problems or issues. I'm fairly savvy and keep things clean, and know how to fix things including nasty viruses.

Suddenly, after the 'Welcome' login screen, the screen would be all black. However, the bottom windows bar ('Start button', date/time, open windows, quick launch) is crystal clear and active (mouseover on an open application and the preview pop-up shows perfectly fine). Also, it seems like the active application window is actually active - responding to mouseclicks and such.

Also, there next to 'Start' is an icon for Switch to New Window and it brings up, showing the desktop as normal, with askew view overlaying the desktop. Clicking just goes back to black. Ctrl-Alt-Del works fine, brings up the normal screen. And selecting task manager, task manager shows up fine.

It's almost like there is a blank black application window open covering everything.

Reboot, etc, etc didn't change anything. Went into Safe Mode and turned off User Account Controls (based on some off the wall suggestion) and surprise it worked!

So, was it UAC? If so, why? If not, what happened?

posted by rich to computers & internet (7 answers total)

Did you try turning UAC back on to see if it came back?

If so, what happens if you mess about with selecting assorted desktop themes?

Is there anything surprising in your user account's VirtualStore folder?
posted by flabdablet at 9:21 AM on June 24, 2011

Sounds like a variation of Reduced Functionality mode Anything from Microsoft not quite ..uh.. authentic installed?
posted by nicktf at 9:29 AM on June 24, 2011

Don't feel confident to risk turning UAC back on.

Not Reduced Functionality... everything works (as is above-board original untinkered with). Just seems like some blank app window 'always on top' of everything (since Task Manager on top usually trumps everything, I imagine that's why I was able to see that when I brought it up).

Not a hardware issue, and after turning off UAC, working fine. There are some references on the problem around the web but most just say the same thing with no cause/reason - they turned off UAC and poof, problem gone.

Just can't find anything on MS' sites on *why*
posted by rich at 9:49 AM on June 24, 2011

What does your startup list look like under 'msconfig' ?
posted by samsara at 10:43 AM on June 24, 2011

UAC, when it needs to prompt you will switch to the Secure Desktop, which is like your normal desktop but with an darkened overlay. Usually there is a non-darkened dialog in the middle of the monitor that asks you to make a security decision; usually to elevate some processes permissions. My guess is that the dialog appeared off of the screen, probably because it is a laptop that you plugged in to an external monitor at some point or you have the external monitor port enabled as an extension of your desktop, and for some reason the prompt is trying to be there, so you can't see it.
posted by jeffamaphone at 10:45 PM on June 24, 2011

That's a reasonable hypothesis.

Windows does sometimes put popup windows in stupid places. If you're expecting to see a window and it doesn't appear, try holding down the Windows logo key and tapping Tab - that brings up the Aero window cycler and should let you bring the window you want to the front. Once it's there, even if you can't see it, hitting Enter usually does the same thing as clicking OK, and Esc usually the same as clicking Cancel.

The UAC permission window is different - it defaults to "deny". So if you're trying to get an "allow" out of a UAC permission window you can't see, you will probably want to hit Tab (to select the non-default button) before hitting Enter.
posted by flabdablet at 11:07 PM on June 24, 2011

I have seen a UAC permission window pop under rather than over, by the way, and using Windows-Tab did bring it to the front. I've also seen the UAC window just take a very long time (over a minute) to appear after the Secure Desktop iron curtain first came down. There are reasons UAC stands for User Annoyed Constantly.

If you plan to leave it turned it off, though, you really should set your computer up with an administrative account for maintenance and limited accounts for day-to-day use. Running Windows while wearing the administrator's magic hat as normal practice really does substantially increase both the risk of getting something nasty lodged in it and the the difficulty of removing any nasty so lodged.
posted by flabdablet at 11:12 PM on June 24, 2011