Just purchased Magix Movie Edit Pro 2013. Installing it went fine, but when I attempt to activate it get the msg An online connection cannot be establised.
Also your firewall may be blocking MEP access to the Internet - although you should have got a message asking if you should allow the program to access the Internet.
It would help if you give us more information about your system and any anti-virus program you have running - see here
I had a similar problem, came up with 'An error occurred while converting the media database. You will not be able to use the database with this product. Please contact support for help with this issue.' Downloaded and sent in a report but then thought I would give it another go by first rebooting, then turning off 'Anti Virus Real Time Protection' and any applications, Skype, WinZip, SnagIt etc. I could and not really required, running in the background. Reran the download and install and this time it worked great, turned 'Real Time Protection' and the other apps back on and everything now seems okay.