Environment: XP/SP3 Sec Center 9 VS 13 PF 10. P4 HT 3.06Ghz, 1G.
I have the same problem, although the duration of the "hang" is about
2 - 3 minutes, occasionally as long as 5 - 6. I first notice that the mouse is frozen (when in Firefox or IE or Word or EXCEL). I now immediately check the tray, and there is the little arrow circling the .... . I am glad that the updates go through, but the freeze seems unecessary.
I am looking to disable auto-updates, and set aside "one morning a week" (thank you Sally Fields :p)null for processing the updates.

sad