I'm experiencing problems with dual screen setup in KDE. Basically, I use my laptop for LCD presentations. Hook up to VGA is usually relatively unproblematic although KDE does seem quite picky about the precise order in which things are done. Get it slightly wrong and I have to restart KDM from a tty. Still, it works fairly well if not perfectly.

The real problems happen after disconnecting the VGA. I've tried various orders of doing this:
- disconnect VGA, wait for the "do you want to configure...?" dialog, configure, continue
- reconfigure, disabling VGA, then disconnect VGA, then wait for the dialog, configure, continue (I've had better luck with this than any other method)

What was happening was that after disconnecting, I would lose the display and would need to switch to a tty and restart KDM or reboot. Occasionally this wasn't required but it always seemed to be needed if I hadn't used the "unify outputs" option (which I don't normally want).

Things have got somewhat worse, however, and what is no happening is that I cannot do anything - I can't switch to another tty to restart KDM, I can't kill X with ctrl + alt + backspace/delete etc. I get a blank screen (but with the backlight usually) or, this week, dark blue and black stripes and then a black screen on trying to switch to tty1). This means I have to switch off with the power button and hope that I can recover the filesystem from the journal information.

A thread about this problem is at https://bbs.archlinux.org/viewtopic.php ... 1#p1079581 but it was suggested there that I post here as well.

Can anybody suggest a fix for this or how I might go about diagnosing and troubleshooting?

It sounds like the graphics driver or kernel may be encountering problems. Do other indicators on the keyboard (such as Caps lock) respond? Alternately, if you have access to another system, does it respond over the network?

Unfortunately, my keyboard is rather short on indicators. There are no LEDs for caps/num lock etc. - the only way to tell if caps lock is on is to type a letter and see the result. Obviously that requires a display...

I don't have access to another machine on the network. When this happens I'm on my campus network and I would have no idea how to access my machine from a Windows box. I could potentially try recreating the problem in my office with an external monitor and then try booting the Windows machine there from a suitable USB key. I don't have ssh running usually but I could enable it temporarily for testing purposes. If I did this, could somebody recommend a suitable distro to put on a key for this purpose? The largest key I have available is 1G.

I'm using the intel drivers. I get the problem with both the lts and mainline kernels from Arch Linux. I also had the problem with versions prior to 3 of the kernel.

You should be able to use Putty on Windows as a suitable substitute to standard SSH.

OK, thanks. Apologies for my ignorance but is that something Windows has already or is it something I'd need to install? I'd rather not install stuff if I can help it but if it is (very) easy to install (and safe), it should be OK. I think I have admin rights on the machine now.

Sorry. I just know nothing about Windows whatsoever which is why I thought booting a Linux USB key might be easier.

Administrator rights should not be required - it is a standalone application which does not need installation.