Vista - I need Help

I have vista basic on dell 1420. This is my new system and i am not IT
professional.
Until yesterday it was working perfectly. I haven't installed updates
released on 9th of Jan yet.
But my computer has following symptoms.
1. My AVG antivirus says "Resident shield is not loaded"
2. Every time i boot up windows asking for some driver to install i dont
know for what. i am using an external hard drive on and often but its
working nicely.
3. I am using an email client from "Incredimail" suddenly windows can not
find its location from program files.
May be my other programs gets screw too ,, i dont know.
I tried to update but i could not update ,, it says error code 800700CB ...

what is going on ??

My volume notification on system tray asways says its mute.. but speaker are
working nicely.

fortunately my internet is working.. so before i loose my connection please
help me out..

Please..........please ............Please...............