Start your browser from within a terminal window. That way you get to see any error message. Your description sounds as if you've encountered a (known, I think) bug in the redhat-install-packages helper utility. You would learn more about it in the corresponding bug report at
https://bugzilla.redhat.com
Instead of a browser, install packages with "rpm" directly. Or get a graphical package utility like Synaptic. Makes much more sense together with freshrpms.net or fedora.us anyway.
But there is also a common mistake with regard to installing rpms. The user picks the src.rpm instead of the binary rpm (such as .i386.rpm or .athlon.rpm). src.rpm contain source code files and don't get installed the normal way, but get only extracted like an archive.