Solaris 2.6 or 7 running on a Sun Ray has the following dtlogin issue 
reported in bug id 4267545.

When the following options are selected from the login screen, the
screen will go gray until the time out period expires:

        Options==>Remote Login==>Choose Host From List

The error does not occur if the same Host Name is manually entered during
the following sequence:

        Options==>Remote Login==>Enter Host Name

To get the fix for bug id 4267545, install the following patches on the Sun Ray's 
server:

        Patch-ID# 105703-18 or greater for Solaris 2.6
        Patch-ID# 108303-01 or greater for Solaris 7.

If an immediate workaround is needed, edit /usr/dt/config/Xsetup and change:

  $DEVICE_LIB/utaction -i -t 900 \ 
    -d "$DEVICE_LIB/Xcleanup" < /dev/null &
to:

  $DEVICE_LIB/utaction -i -t 900 \ 
    -d "$DEVICE_LIB/Xcleanup"  4</dev/null &


The change will be effective after a server reboot