The solution is posted in comment #12
Run the following two commands as root
rm -f /var/lib/rpm/__db.*
rpm -vv --rebuilddb
First, remove the corrupted rpm database.
Second, rebuild the database.
I am using, nor have I ever run, pclinuxos. I just went to the link and read the thread. Although the users seem to know what they are talking about, I can not attest that the commands will work.