Windows Modular installer stopped working

I am running windows vista home premium it was an up grade from XP home
premium and I use Norton 360.

I have been working with HP tech support for a week now because my computer
will not install updates. The computer will begin the installation and then
freeze during the first update installation. The error message that I get
says that the Modular installer has stopped working. I have tried to clear
out my distrubution files, deleted all the updates that it would delete;
stop, start, and restart the windows installer. I even went in DOS to try to
fix the problem with WUSERV.DLL among other commands and nothing is working.
Now my computer will not even search for upgrades. I have no internet
connection problems. Someone please help! I do not know what else to do.