I recently came across this problem. I have a Centos 5 server that I tried to update using yumex. I selected the updates I wanted and tried to apply the updates. Yumex started to process but would hang before any of them were installed.
I tried to install one update at a time to see if it was a conflicting rpm that was causing the issues. It wasnt.

I then used the folling command to rebuild the RPM database

rpm –rebuilddb

It took a short while to run but after the rebuild my yumex ran successfully again.

It may not be the only way to solve this problem but ItFixed it for me.

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