I recently installed 2012 on my developer box, and a coworker did as well (in a team of 8). Only the 2 of us noticed almost immediately an issue running our existing application using 2010. Specifically the error we get during run-time is:
Information about the domain could not be retrieved (1355).
Like I said, this issue only occurs for us 2 that have installed 2012, noone else on the team has this problem. We've searched high and low and only found threads discussing the same concept (that the problem occurred after installing 2012).
At this point, I'm not even sure uninstalling 2012 will fix the problem (as the damage is probably already done) and unfortunately no System Restore points exist for me for some reason?!