Comment 6 for bug 995646

I was having exactly the same problem:

Installing Restricted Extras, Ubuntu 12.04, HP Pavillion 6000, 64-bit.

The Ubuntu Software Center froze at about 70% of Restricted Extras.

I was researching workarounds, found this page, had decided to go back and use synaptic, and before I could kill the in-progress install....it kicked in suddenly and finished. I did not time it but I'm pretty sure it was well over 10 minutes; and I just clocked my internet down-link speed at 5.9 Mbps. I am wondering if perhaps there is some hangup at the server dishing up the Restricted Extras to Ubuntu Software Center?! I have no way of knowing if the source had been completely downloaded or my machine was waiting on more data. If Synapse is grabbing Restricted Extras from a different server that might be an explanation for why it works better.

At any rate, I did experience this stick, but then it finished installing; and the Ubuntu 12.04 was a totally fresh install on a newly formatted partition this afternoon (Restricted Extras was the second new thing I installed after Chrome)