Hi Kevin,
The RHEL/CentOS 5.4 and 5.5 versions were corrupt, likely due to issues
with the python compiler.
The builds have been fixed, and uploaded to our ftp server, as "6.3.0a" revisions:
qubegui-6.3.0a-release.x86_64-RHEL_Server-5.4-x86_64.rpm
qubegui-6.3.0a-release.x86_64-RHEL_Server-5.5-x86_64.rpm
Please download the appropriate one for your platform, and reinstall.
Thanks for letting us know, and sorry for the trouble!
-shinya.