Adobe recently updated their site, and on the left side you should see:
"Need Shockwave Player for a different computer?"
From there, it lets you choose your OS and you can also choose whether to download the full or slim version. That's how I do it, at least, and I've never had any problems with Shockwave. That's the only suggestion I can think of... other than trying to downgrade again. I remember months ago Jasmine said in a thread that a specific older version worked best. Do you know which version you downgraded to? I'd try 11 if I were you.
Good luck :S
I'm still looking into that first popup, by the way.