Les, I've tried my Harper's links back to March. All OK, so not a time problem.
Tried all your links, including the Triple, back to the August JE grid. All worked except that one.
Also, your March solution gives a 404 (page not found) error as well.
First possible is that you've deleted, renamed, or moved the puzzle to a different folder at Dropbox.
Second oddity is the conversion of the title. Numbers following a percent sign are hex ASCII code.
e.g. %20 = space, %26 = &
The latter doesn't get translated.
http://dl.dropbox.com/u/57742443/August%20Joint%20Effort%202012%20Grid%20%26%20Clues.pdf
appears in the address box as;
dl.dropbox.com/u/57742443/August Joint Effort 2012 Grid %26 Clues.pdf
I tried typing it but no success.
Tested with the Chrome browser which doesn't convert the code. Same result, 404.
Beats me. You might try contacting Dropbox tech staff.
@theambler Next time download them right away. I was going to post it, but appears I've neglected to do that too. Bummer )-:
Les, can you send me a copy of the August puzzle? I have the rest.
Thanks.
http://www.crosswordsolver.org/forum/264375/the-august-joint-effort-crossword-2012