Use the force
Feel like you're chasing your tail? Hmmm....
You can try using rpm -Uvh --force RPMname.rpm . In all likelyhood it will install even though it is already installed. (Of course it doesn't fix the original issue/error you had in the first install). Note the double dash before force.
You can also use the --test switch to see whether it thinks it will work before you actually commit to the installation.
If the rpm was corrupted in the download, rpm should have refused to run indicating a checksum error in the package file.
Hope it solves your rpm problem.