Diablo III cannot complete installation and reports that the servers are unreachable or busy.
This is because CrossOver cannot find the new libgnutls package which is caused by an update to the Debian package name.
For now, if you create a symlink to the name CrossOver expects to find, you'll find Diablo III works via CrossOver.
We are working to fix this permanently in CrossOver but for the time being, this will get you fixed up.
First, install the new version. With root privileges:
apt-get libgnutls-deb0-28:i386
Then, create a symlink. With root privileges:
ln -s /usr/lib/i386-linux-gnu/libgnutls-deb0.so.28 /usr/lib/i386-linux-gnu/libgnutls.so.28