A lot of things can impact automatic downloading - not a whole lot of detail to offer helpful solutions.
I don't know of any particular issues with VCRM 7.3.1 impacting autodownload... I have long been a fan of not relying on autodownload... any time a new SPP is released I simply download it directly to the repository and let VCRM extract it. Everytime I'd do a .0 upgrade I'd always clean out the repository and re-populate it or create new repository for VCRM if customer wanted to maintain the old one for a time.
