I had exactly the same problem when I first started using Audirvana Plus. Here is the link to my post on Audiogon concerning this problem; and more importantly, the fix!
http://forum.audiogon.com/cgi-bin/fr.pl?icomp&1353690494&openfrom&2&4#2
http://forum.audiogon.com/cgi-bin/fr.pl?icomp&1353690494&openfrom&2&4#2