Avast! v5 Installs Just Fine. I Just Can't Get the Program To Open

I have the latest version of Avast! installed on my laptop, but I can’t get it to run. When I click on the shortcut on the desktop, I get this message:

C:\Program Files\Awil Software\Avast5\AvastUI.exe
This application has failed to start because its side-by-side configuration is incorrect. Please see the application event log for more detail.

What does this mean? How do I fix it?

I had a similar problem in my syster’s vista ultimate 64 bits computer and it got solved installing the next servicepack availible for vista.

rm