The build server that produces RPMS for the software repository for PCLinuxOS has switched over to RPM 4.8.x as of today. This comes after a month worth of notices and reminders posted.
If you are running a PCLinuxOS 2010 installation and haven’t installed and ran aptupgrade you will no longer be able to install new packages from the Synaptic Software Manager.
You do not need to do anything if you have recently installed PCLinuxOS from a 2011 CD.
More Information here on how to install and run aptupgrade