Was having this issue yesterday but I had upgraded php version prior. Today I performed a clean install of virtualmin and attempted to install zen cart via the install script. The same problem has occurred again at the step of saving the database settings. When I click on [Save Database Settings] i get this error:
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, root@localhost and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log. Apache/2.2.3 (CentOS) Server at gmg.greenmonstergraphics.com Port 80