1. Delete your Prefetch.
2. Delete AVA Logs
3. Delete AVA Xigncode and leave x3.xem and xnina.xem
4. AVG antivirus can be a b*tch. It likes deleting AVA.exe. Add an exception for the whole AVA folder.
And if it still doesn't work, try reinstalling AVA.
EDIT: AVG can also block it so that the file remains but can't be accessed.
EDIT 2: You have to reinstall to get the AVA.exe file back if it has been removed by AVG.