Add/Remove Applications freezes

I recently installed 8.04 and in the course of trying to get everything set up, i have run across a small problem. Whenever I go into the add/remove application and try to install a new program, it will start the little spinning circle and sit there forever doing nothing.

I had a similar problem with the update manager and I found a fix here: http://ubuntuforums.org/showthread.php?p=4896524#post4896524

any ideas? everything else seems to work, updates work now, and synaptic will install packages normally, so why is this freezing?

I'll include a screen shot although it probably wont tell you anything new, it simply freezes when it's grayed out and stays that way; eventually i end up having to close it with the system monitor.

http://i25.tinypic.com/27zj2oy.png

Thanks for your help,

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