It could be an odd interaction with graphics device drivers.
Usually when things go wrong with ADE2.0 my immediate reaction is to try the older but more reliable v1.7.2.
I hadn't heard of 2.0 failing in this way, especially after working before, but might be worth a try.
Version 1.7.2, it is a little difficult to find, available on Adobe site for Windows and for Mac.
The forum software is sometimes corrupting the link above. There shouldn't be a blank in 'editio ns.html'. The following redirects to the same page: http://tinyurl.com/diged172
I assume you pointed your finger in the right direction.
I updated this day my Intel HD graphics driver to 18.104.22.16871.
Problem came right after...
It may be related...
Thank you so much for your helpful assistance. I am going to install the version 1.7.2
Should I expect some issue with my registered ebook ?
As long as you make sure 1.7.2 is registered with the same AdobeID as ADE2.0 is, you shouldn't get problems.
Sometimes ADE gets confused registration; that can happen when you first install a new version.
In that case, you need to remove the registration from the version giving problems (ctrl-shift-D, cmd-shift-D on Mac), restart ADE, and re-register with your AdobeID.
If your ADE2.0 is working OK I would bother to use v1.7.2.
Just remember it's there if you get other issues that seem to stop 2.0 working.
You can have 2.0 and 1.7.2 installed at the same time.