Suddenly today, my pgAdmin application become useless, and just starts and flickers. I didn't change anything with pgAdmin. Yikes, but I just remember that I installed a distribution of python from the internet that has it's python interpreter configured in the path environment variable.
The solution, of course, remove the entry of any python interpreter from system environment PATH variable and start pgAdmin. It works.
Interestingly the version of python that pgAdmin uses is 2.7.11 and the one I have installed is 2.7.12. So it's definitely not the interpreter that's the issue, but the python virtual environment configuration (venv) that pgAdmin has is setup with all necessary packages to run pgadmin, whereas my local installation is empty. So that's what is making this to crash.
Have a good time. :-)