If anyone having the issue could actually test the beta and report back if the problem is really solved, it would be greatly appreciated.
The proposal of the OP was exactly the opposite: Avast Team could/should participate at those MS forums to "publish" the new beta, minimize the impact of those "uninstall Avast completely and forget about it" suggestions, and finally Avast could have some more testers about the issue.
Since the issue is actually a crashed system, I don't think that users are waiting for the stable release. They either accept using a beta (if they actually know that the issue may be resolved), or they change to a different tool.
Avast should had released a new stable with at least this issue resolved (and any already solved critical problems), if not for the users of Vista "pre SP2", for the bad PR. All the "extra" (read, non-critical improvements) could have wait in the beta step. Just my opinion.