External display issue with my Toshiba notebook

I have a Toshiba notebook with two video outputs HDMI and VGA. I have been using this setup without any issues for years. The HDMI monitor is the primary one, the VGA serves as a desktop extension. Then one day I run a PowerPoint presentation and since then I have the following issue: the system boots normally, I can see the Windows logo on my HDMI display, but when Windows is done booting, the monitor goes black and nothing happens. As soon as I lift the lid of the notebook just a bit and drop it down again, the image restores on both external monitors and works without problems.
I have tried everything - BIOS settings, reinstall graphic drivers, using a different cable, look through monitor settings, change driver settings, connect and disconnect monitors one by one and restart Windows, even launch PowerPoint presentations in different modes to see if it maybe fixes itself - nothing helps. Any ideas?
Thanks in advance.