Installing Avast anti-virus causes 'guru' unless Vista32 guest in 'safe' mode

[Occitan]

Happily and reliably running Vista Home Premium as guest but if Avast free anti-virus is installed it reliably goes into 'guru meditation'. This can only be avoided by running in 'safe' mode in which avast does not start. Removal of 'Avast' restores normal reliability to the guest. This pattern was repeated several times as I repeatedly downloaded and reinstalled Avast to to try to ensure that the download of Avast had not been corrupted. An additional factor may be that the guest Vista has had a Norton backup of a Vista image from a historical machine of mine (now defunct) restored to the guest. But having said that, it works reasonably well as long as Avast is NOT installed. The only reason I would like to install Avast is that Microsoft Security Essentials appears to have been deliberately prevented from installing on Vista machines since support for Vista ended but a virus-defence is still necessary. Ticket #13899 also mentions Avast.

[Occitan]

As Requested by Guru Screen

[Socratis]

This is most probably a duplicate of #4816, #8545 and #16356.

The usual suspect is VT-x being disabled in the host. Unfortunately the 3 (why?) logs that you included do not seem like the standard VBox.log, so I can't know for sure.

[Socratis]

Closing as Duplicate of #8545.

Avast requires VT-x availability on the Guest (or anything else that gets installed on). This VT-x availability was not an option until 6.1.0beta.