Formatting issue with PC {update issue?}

Hi Caroline or anyone else experiencing problems with the cross-over between MAC and PC with their theme design. My blog design appears wonky in that the post navigation is uncoded and everything seems zoomed in. This problem arose when I updated my SPUN theme by Caroline Moore and it as a result is no longer compatible with my PC but is fine with my MAC. I am hoping someone can offer me some advice on how I can resolve this because as of now it is not viewable from a PC. PLEASE HELP ME!!!!