I contacted EA support first, and received a literal copy and paste - word for word - from google of the answer that I already found through google myself before even contacting support (which didn't help). I tried to find a serial number that I may have missed through Steam, no luck. (I never entered a serial number, nor received one - I assume automatically done).
About a week ago, I reinstalled the game and received the error a fair number of other people seem to be having - Invalid serial number entered. At the time, it downloaded, installed and I played it for a few hours without any issue.
Information, Guides and Announcements for the EA appĪ year or so ago, I bought Dead Space 2 from Steam as part of a bundle.