Software Update hangs

My Software Update has suddenly stopped working. It hangs at "Checking for new software" and the progress bar is at about 10%. i've searched all over and have done a few things, but can't seem to get it working. i've tried removing com.apple.SoftwareUpdate.plist and removing everything in /Library/Updates. I've tried clearing cache files and repairing permissions (via Cocktail.) I've used Disk Utility to check my drive for errors and it didn't find anything. I also ran the hardware test on my original Tiger restore disc and that didn't find any errors.

It is similar to this thread:

http://forums.macrumors.com/showthread.php?t=251842

Anyone have any ideas? I've tried just about everything I can find and can't get it to work.