This problem typically occurs on Windows 2003, and is indicative of a bad installation. What happens is the two RME package directories, NMSROOT/www/classpath/com/cisco/nm/xms/psu/pkgs/rme and NMSROOT/MDC/tomcat/webapps/rme/WEB-INF/lib/pkgs become out of sync. Those two directories must have identical contents in terms of .zip files. When the former directory has a package that the latter does not, PSU will think the package is installed, but RME will not.
While you can copy the contents of the former directory to the latter, you may have other installation-related problems, and a reinstallation from scratch is always safest. Before attempting the reinstallation, you should set your global and per-user TEMP and TMP environment variables to something short like C:\WINDOWS\TEMP, then reboot.