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I'm trying to set up a machine here with Ultra VNC on Vista with UAC off. Problem is, in this configuration, I can't send Ctrl+Alt+Del to the Vista machine and so I'm stuck at the login screen, which is waiting for the CAD sequence. I'm joined to a domain, so I don't think I can disable the CAD requirement. I can't re-enable UAC either. I also tried using the on-screen keyboard, but it didn't seem to work. Any workaround or solution?

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right click on the menu bar, not the item in your task bar – user33400 Apr 6 '10 at 16:10
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protected by studiohack Apr 27 '11 at 1:13

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8 Answers

Doesn't VNC have a feature to send CAD? With RealVNC you can click the VNC-window's icon (at the top left corner) and click "Send Ctrl-Alt-Del". Maybe there's something similar? Otherwise you can of course use RealVNC's client.

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That's the problem. Something on the server end has to actually send the CAD once it has been instructed to. On Vista that's broken because of the changes to session isolation. – jasonh Oct 11 '09 at 4:15
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After much searching, I gave up and set group policy on the machines to not require Ctrl+Alt+Del.

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I wrote a library called SasLibEx that can simulate the CAD keypress, even when UAC is disabled. Some om my customers use it with UltraVNC: http://forum.ultravnc.info/viewtopic.php?p=71476

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There is a known issue with CAD and window7/Vista with UAC

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Set your UAC level to the 2nd lowest. This will allow you to send Crtl+Alt+Del to the remote computers through VNC and other remote software.

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Setting the UAC to the 2nd lowest level worked for me, i use Windows 7 Ent with UltraVNC. It takes about 5-6 sec for the command to go through, but it works. Thanks who ever gave that answer, saved me a bunch of time =D

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The latest release of UltraVNC and VNCScan have resolved this issue. There's a pretty thorough post of it at http://vncscan.com/blog/2010/09/ultravnc-and-windows-7-ctrlaltdel/

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There is a registry setting that can be changed that will allow Ctrl+Alt+Del to work. I'm not sure what the setting exactly is, as the incorrect setting was detected by VNC and provided me with the option to make the change itself. Here's how I went about it:

  1. Log in to the remote computer (so that when you connect via the VNC Viewer you won't be prompted with the "Ctrl+Alt+Del" screen).
  2. On another computer, use the VNC Viewer to connect to the remote computer.
  3. Press the Send Ctrl+Alt+Del to Host button on the toolbar. At this point, the VNC Server shows a message "uac is diable, fix registry." Click OK.
  4. After this registry fix, Ctrl+Alt+Del commands works as expected.

This post gets credit for pointing me in the right direction.

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