I think the problem is you ran the installer as root, so all the files were created with root permissions. Just do
$ sudo chown -R starfire:starfire /home/starfire/PlaneShift/
Of course, I'm assuming starfire is your username. If not, just replace starfire:starfire with your username:groupname.
I'm also assuming the problem directory is PlaneShift.
You could also run the same command on your downloads directory just to be sure (nothing will happen in the worst case).
Finally, run
$ ls -l
to see if there are any files or directories that don't belong to you on your home folder, and if so, change their owner, too. They should all say "starfire starfire" on the third column.
Remember to only do this to the files you're supposed to own. That is, don't do this to anything outside your home directory, unless you really know what you're doing.