Quicktime software won't install

After I've downloaded Quicktime from the Software Update, it required me to restart the computer. When the computer's restarted, the installation for the quicktime update begins but it gets stuck at configuring installation. I waited for hours but still the installation does not progress any further than configuring installation. Help! What should I do, how do I fix the problem? I already tried reformatting the whole computer and it was successful, but the software update gets stuck at configuring installation.