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SDB:YaST lock files
tagline: From openSUSE
You can't use software install because "an other yast session is running", but there are none.
Chance is you crashed or broke your X session (Ctrl Alt bckspace) during Yast session using the rpm database.
Yast creates lock files not in /var/lock as usual but in /tmp. Search for "yast*" and remove the files found in /tmp don't do this if a Yast session is really running!. (tested on 10.2).