What you are showing isn't the boot-time scan but the initiation of the Simple User Interface by using the ashAvast.exe icon on the desktop, is that what you are doing ?
If the first bit fails then I wouldn't expect the second part to work either.
Try a repair of avast. Add Remove programs, select 'avast! Anti-Virus,' click the Change/Remove button and scroll down to Repair, click next and follow.
First you shouldn't have to use that ashAvast.exe shortcut, but right click the avast 'a' icon, select Start avast! Antivirus. Try that, does it work ?
If not try launching the C:\Program Files\Alwil Software\Avast4\ashSimpl.exe file directly, does that work ?
Have (or did) you another AV installed in this system, if so what was it and how did you get rid of it ?