"open with" spoils installation of haroopad v0.13 under Win7

I installed haroopad v0.13 under Windows 7 32bit and Windows 7 64bit.
I could start the program. No problem.

Then I selected "haroopad.exe" as optional program in Windows Explorer for "open with" for .md files.
Afterwards, haroopad could not be started any longer. Using Process Explorer I noticed that actually two processes haroopad.exe are running. One is the parent process of the other.
The child process is started with the following command:
"C:\AK\Programme\Haroopad\haroopad.exe" --type=renderer --enable-threaded-compositing --no-sandbox --lang --nodejs --working-directory="E:\AK\tmp\nw6092_31519" --device-scale-factor=1 --enable-delegated-renderer --channel="6092.1.1122022847\1673484501" /prefetch:673131151

The child process has a thread looping in haroopad.exe!SetCrashKeyValueImpl+0x3701
It is not possible to bring this process to the visible front.

Re-installation of haroopad does not work. I am stuck!