I'm running Mac OS X 10.6.8 on two computers. I downloaded the update on one and it only downloaded to 95%. I used the uninstaller and tried an archived version (10.1) which immediately errored out.
I had left the older version on the second computer. Today at 12pm, it said that flash was out of date and showed "blocked plug in" message on all websites using flash, thus forcing me to download 11.6. The download again only went to 95%.