This resolved my issue. Thank you! This topic can be closed/moved.
I read the EAQ, and this specific error was included. However, I am currently running 1.7.4. I know of no way to patch to 1.7.2. I have never run 1.7.2, as I have not played in almost a year and only just updated today. I therefore have no 1.7.2 version listed in the version editor. I am using vanilla minecraft - deleted my .minecraft folder in Appdata and deleted the .exe, redownloaded it from the official site and re-updated just to be sure, but also used vanilla profile before the wipe. I am using the latest version of the Forge .jar from files.minecraftforge.net. I continue to get the error. I would post logs but there are none to post (it's not that I can't find them, it's just that none are generated). Is there a way that I might be able to patch to 1.7.2? Am I just missing something obvious and being completely stupid? Please let me know either way.