Problem:

Under OpenSUSE 11.x and Plesk 9.x and above yast might not work anymore. This probably happens due to a faulty Plesk file.

The error message in the console looks as follows:

suse-server:~ # yast
//sbin/yast: line 27: //lib/YaST2/bin/yast2-funcs: No such file or directory
//sbin/yast: line 238: set_lang_from_sysconfig: command not found
//sbin/yast: line 267: check_ncurses: command not found
package yast2-qt is not installed
package yast2-gtk is not installed
Something is wrong with the YaST user interface.

Fix:

In the file:
/etc/profile.d/courier-imap.sh

change the first line from

if echo "$MANPATH" | tr ':' '\012' | fgrep -qx //man

to:

if echo "$MANPATH" | tr ':' '\012' | fgrep -qx /usr/share/man

After logging in again via SSH yast will be working again.