Laptop suddenly stopped detecting projector via HDMI

Hey guys,

Having a really strange problem and have tried everything from system restore to a point where I'm sure it worked, to uninstalling/reinstalling all gpu drivers etc. and I'm completely stumped.
Was working fine the other night, turned it off, then went to use it the next night and just wouldn't work.

Firstly, It's a Lenovo Z510 laptop, with an i5-4200m, nvidia 740m and running Win7x64.

So.... Up until a few days ago, when I plugged in the HDMI cable when the projector was on, it was instantly detected.
I then could select to clone or extend, or just to display on the projector.
Now when I plug in the HDMI cable absolutely nothing happens.
Nothing shows up under extra displays, forcing a detect does nothing either.

Right, now this is where is gets a little strange. When the pc boots with the projector connected the bios & boot screens display on the projector, but as soon as it reaches the desktop the signal is lost, and it shows no external device connected.

Now, it gets even stranger..
While in windows with the projector connected, if I then install the drivers for the integrated HD4600 over the existing ones, as soon as the installation completes the projector detects and works flawlessly as before.
BUT... I can't select restart to complete the installation, because if I do, when it boots back to windows again there is no signal. So back to square one.

So the only temporary workaround i can find is to connect the PJ, the reinstall the integrated gpu drivers and don't reboot.

As I said, it was working one night and not the next. Extremely bizarre situation.

Anyone experienced anything like this, or can you suggest any possible reason for this happening , or any ideas on how to fix it.
I'm completely stumped!!!

Thanks,

Mark.

'I plugged in the HDMI cable when the projector was on' -

I don't normally use HDMI but had to buy one recently. There was a message in the packaging along the lines of 'make sure all equipment is powered down before connecting this cable or damage may occur'. I followed the advice and had no problems. I didn't bother testing the theory by hot-swapping HDMI with the new (expensive) build. I'm sure folk on this forum will say they have been hot plugging for years with no issues, but apparently the plugs have a +5V pin for some reason and it can cause damage. Hope I'm wrong in your case but ... my 2 cents anyway.

Thanks for the reply mate. I thought hot plugging was ok? Anyway I tried booting with the cable in and no luck. The bios and boot screen show on the projector then the signal drops as soon as it hits the desktop. Really seems like driver issue but tried everything I could think of and still no luck. As I said, was working one night and then not the next. Still the only workaround I have found is to reinstall the hd4600 drivers and not reboot whenever I want to use the projector.