Issue related to AVG Free

I am running XP pro SP3 on a couple Dells. I had AVG Free om my system for most of the last year. I installled in with V-9 and it updated to V10. When it came out with V11, I got a message that I should upgrade to V11. I downloaded a file
avg_free_stb_all_2011_1170_upgrade 4,397 bytes in size & ran it. It went through the install process and came up with a message that I had to reboot. When I did several times, it still comes up with the same message that for AVG 11 to be run, I have to reboot the computer.

I found your forum and the questions others had about AvG & I decided maybe I had a defective download & tried the one you have on this forum
I copied avg_free_x86_all_2011_1188a3311 and got a file 149,311 Kb and it appeared to be complete. I tried installing it & it showed a progress bar completing. Once it was done it returned my system to me, but never installed completly. When I tried rebooting the computer it still says I have to reboot to get V11 active.

Does anyone have any ideas what I need to do to fix this?

Thank you in advance for any help you can offer

Ddh
Troy NH