Sometimes after an upgrade it's just a matter of your regular user not have the rights to record some needed info in the registry, so it keeps trying again every time you launch Sage 50. Instead of launching it the usual way, right click on the shortcut and choose Run As Administrator. Answer yes or allow to any prompts that you get. Once it opens, you can exit Sage 50 and try launching it again the normal way.

Thanks. The issue just stopped, on it's own.