Sounds like you are trying to install an HTML file :-)
Try downloading it again, and check the RPM with "file".
(viewing the file probably works too, maybe an error?)
$ file CB_20061102_rev3170_fc4+5.rpm
CB_20061102_rev3170_fc4+5.rpm: RPM v3 bin i386 codeblocks-1.0_0.svn.3170-0.fc4+5