I'm still using 2010, so I don't really know, but I can't believe that 2012 broke splines quite that badly. I would shut SolidWorks down and reboot my machine before I got too worried. Sometimes SolidWorks just gets its knickers in a twist and needs to be banged up along side the head with a suitable 2 x 4.
I seem to recall that the last SP of a particular year of SolidWorks was going to be able to open files from the next year's version, but I don't recall if it was Rev 5 of 2011 being able to open 2012 or the last release of 2012 being able to open 2013. Maybe you are in luck.