I'm not sure why RPM would fail to uninstall packets, but it shouldn't be too hard to work around. When you install LabVIEW again, use the --force command with RPM. This will force it to overwrite all the files. There are a couple of oddball problems with install scripts in RedHat 7.1, so you might want to just follow the instructions and use RPM to install things manually using the --force parameter.