Do you experience problems during downloading?
Check your connection in Status and Interface settings window.
Use Test Server in Config > Servers.
We will probably ask you to do a test using only basic settings.
Do you experience problems during repair or unpacking?
Enable +Debug logging in the Status and Interface settings window and share the relevant parts of the log here using [ code ] sections.
If you unpack the ZIP distribution file and run the SABnzbd.exe file in that,
you should get a Windows popup stating which DLLs are missing.
Can you try that and tell me what the popup says?
OK, that means that you already have the required Microsoft DLL files.
The detection mechanism in the installer fails.
Thanks for the update, I must do a bit more testing.
One issue is that almost all Windows versions have the DLLs out-of-the-box.
So testing it is tricky.