If you get this error in plesk when you are trying to create a new domain, chances are you moved your /var/www/vhosts to a new partition or disk with more space, and you forgot to copy the .skel directory to the new partition.
I got the following error when trying to install Plesk on a fresh installation of Red Hat Enterprise v5.3:
ERROR: Unable to install the "psa-8.6.0-rhel5.build86080722.01.i586" package. The following could cause the installation failure: Packages "bind-libs-30:9.3.4-6.P1.el5.i386" and "bind-libs-30:9.3.4-10.P1.el5.i386" cannot be installed at the same time because of the conflict on the file "/usr/lib/libbind.so.4"
So I ran
yum erase *libbind*
and boom, it started installing.