From MDLWiki

[edit] Problems with AVG Anti-Virus

AVG couches a big problem with Messenger Discovery Live. With AVG installed there's not way to be installing Messenger Discovery Live. There is no easy and fast solution available yet to get this working.

The only current solution available is to completely uninstall AVG from your computer, install Messenger Discovery Live and afterwards install AVG or any other anti-virus program again.
After installing AVG again, you'll be notified that Messenger Discovery Live contains a Trojan Horse, which offcourse does NOT, but you can ignore and heal this file.

[edit] Compatibility

MessengerDiscovery Live 1.4 is not detected as a virus by AVG. So, if you are using an older version of MessengerDiscovery Live, you can download 1.4 from our website.
MessengerDiscovery 2 is also not regarded as a virus by AVG. MessengerDiscovery 2 is set for release late 2008.