Web Interface display configuration

Hi,
I´m using Logitech Squeezebox Media Server v 7.7.5 on WIN7 Pro x64 System.
Since some time only the "Light" or "Classic" Web-Interface can to be choosed
but no longer "Standard" which is the most convenient Interface version.
In the light and classic version additionally no music-folders or music-titles can be added to the playlist.
I cannot tell what happened or what have I done in error that produces such issues.
Can someone help please?
Is there perhaps a newer Media Server version available ?
Many thanks.
draisi