Comment 19 for bug 187982

A simple workaround that works in my case (while the bug is fixed):
1. When you get updates notified, open the update manager as usual
2. Instead of installing the existing updates (this will produce the problem we all have), pres Check for new updates. This will ask for the admin password and will work correctly. You will obtain the same list of updates.
3. Press Install the updates. Since the admin password was entered in previous step, it will not be asked for again
Voila!

PS: My system is quite up to date hardware wise, I don't think it's because of it being slow (Core 2 duo extreme, 8 Gigs of ram ...) running Hardy. Previous version (Gutsy?) worked fine