Not sure if this is the same issue but there’s been a known problem with flickering in Retail WoW with every v460xx Nvidia driver so far since they were released last December; details here in this thread:
According to the release notes in v466.47 released May 18th, the issue is still unresolved.
This is the first I’ve heard of anything in the Classic clients, though, so what you’re all experiencing may be a different issue.