BSD when installing Avast 5

Had avast 4.8 latest version.
Installed Avast 5.0.
Got a Blue Screen Of Death.
Made a system recovery, back to before installing 5.0.
Both 4.8 and 5.0 is gone now. At least I cant find them anywhere in my programs or on my hd.
Tried to install 4.8 again, but an error stopped the installation.
My security center, states that 4.8 is installed and updated.
There is no Avast listed anywhere except security center. I have no icons on my desktop,
and no sevices running, if I look in task manager.
What now ???

Vista Home Premium, Danish

Try the Avast Uninstall Utility and try again:

http://www.avast.com/en-gb/uninstall-utility

Thank you .
Solved the problem.

But…I am unable to registrate 4.8.
When i am trying, the browser is unable to open registration site.