Adobe Flash crash fix not effective on all sites

I'm running Firefox 3.26.28, which has suited me fine. Yesterday I made the mistake of "upgrading" to Flash 11.3 & met the endless crashes described elsewhere. Figuring that returning to Flash 10.3 might get Firefox working again, I uninstalled 11.3, downloaded the 10.3 installer, & successfully installed 10.3. Firefox is stable again & Flash works at (for example) YouTube. However, if I try to add a photo to an eBay sale page, eBay (?) puts up a message saying I can't use its better photo gadget unless I install Flash, that is, it no longer recognizes 10.3, even though it did previously. I hope there's a fix here, because I don't expect much from Adobe or eBay.