Getting an issue where on my Windows 7 SP1 64-bit machines chkdsk (autochk) stopped working, it gives an error where it notifies you that recently installed software prevents you from checking the disk. Uninstalling avast restores my ability to use check disk.
Exact error : Autochk cannot run due to an error caused by a recently installed software package.
I came across chkntfs the other day (didn't know it existed). Apparently people have used it for Windows having this problem and not necessarily tied to Avast. I think they boot into a recovery environment command prompt and run the tool, reboot and then run a chkdsk /f normally to verify the filesystem is clean. Take a look and see if it helps you.
https://support.microsoft.com/en-us/kb/160963 I can't tell you why it might only be happening every time you install Avast though, sorry.
