the software update server is not responding

Are you connected to the Internet? If you are it sounds like a problem at Apple's end. Occasionally this happens. Wait a few hours and try again.

Best of luck.

I just updated to OSX Mountain Lion and was trying to install the HP and Canon Printer and Aperture updates. The Aperture update installed fine, and now the App store software is "stuck" on the OSX Software Update part and says "Waiting ....." I can't restart the App Store program and also can't reboot .... How long will this last?

Are you using that school's software update server? You may need to contact them.

You can also download available updates and install them manually by going to this page on Apple's site.

If you have the software install disk(s) that should have come with the machine you can reinstall the operating system. I don't understand why you can't manually download updates from Apple's web page, though. Go there, get the installer files and then run the installers.

The other thing you can (and probably should) do is set the computer to use Apple's servers for the software update. Yours is set to use some other site. Change it by going to the following location - Your hard drive > Library > Preferences and look for a file called com.apple.SoftwareUpdate.plist and delete it. This will set where it looks for updates back to default, i. e. on Apple's servers.

i have this same problem- I have tried deleting the .plist files multiple times and it is still not working