Omid, in the recent past I used AVG Free, until their latest program update (2011) started interfering with one program on one computer and wouldn't update itself on another computer.
This shouldn't be due to a change in QuickBooks, since the QuickBooks isn't even installed on this computer; I am merely storing the install CD. Very strange.
Igor, I am not sure how to check the QuickBooks file, other than by installing it, which I really do not need to do on this computer.
Aisuser, it is very strange how you got the same message regarding a MSWorks setup file.
I'll bet there was a smal change in AVAST which is causing it to stop reading certain setup files or CD's. In my case there are two files mentioned in the message, the Windows XP setup and the Windows 2000 setup.