I would be interested to know why it is not possible to run Avast antivirus in Safe mode.
When attempting to do so:
"Sorry we've crashed".
Why do I want run Avast antivirus in Safe mode?
Because there would be less applications running while carrying out an Avast "Full Virus Scan", that could potentially (particularly if there is a virus Threat") interfere with detection or action on any Threats, and likewise take up system resources and thus I assume, such an Avast scan could take less time.
Why do I want to run Avast antivirus in Safe mode rather than carrying out an "Avast Boot-Time Scan"?
It would just be an extra option, but I have also encountered an issue when attempting to download for the "Boot-Time Scan", its "Specialized antivirus definitions" (as I put to discussion in two recent threads).