Yes, I tried that delete question function, but it left about 4,300 questions still in existence! That's why I'm now trying to fix them instead.
Yes, I'm testing it on my development server. No way would I do it on the live version until fully tested! I'd be drawn and quartered :P
As to where it's coming from, I can tell you that now: Moodle 1.9 courses that have been restored/imported over and over into new ones and never fixed! Sigh. Where THAT original bug came from, I don't know. All I know is that it keeps perpetuating itself.
Thanks for your time, Tim. I appreciate it.