Time Machine Not Functioning

[D-macdude]

This is not happening to my computer personally but I recently installed Leopard on my mom's Mac Book Pro and I set up Time Machine with a brand new external hard drive that she had gotten, solely for Time Machine. Now I'm having trouble viewing the Time Machine Backups with when I click the icon and it goes into "space mode" etc. It is backing up though because when I enter the hard drive manually it shows the different back up days and the changes--it just doesn't seem to show the changes when I click the icon, which, to me, is the whole purpose of Time Machine. Now I don't know if her hard drive is formatted wrong and maybe that could be the problem. Right now its formatted to Mac Os Extended, (Case-sensitive, Journaled). Thanks for all the help!