Just to say thanks for the above. Didn't work but for anyone else, here's what happened:

I switched to a new hard drive a few months ago and now I have the "Please select a value between 8 and 8" for temporary internet files, which stops proper caching. At this point I'm resigned to it, because the solutions from this point entailed changing windows software and it's not that big a deal. But if you're having this issue you can google the above quote if you're that desperate to fix it!