Look in your temp folder for a directory with an alfanumeric string (for me {E1F84AB6-D46A-43C7-A056-D3C7795DBB21}), and read the rtpatch.log file. It will tell you what file it crapped out on.
This is my problem, but no matter the source, (have tried using the file from cd, from download, etc) the installer is hating on Sims3GDF.dll . Oy. INVALID FILEEEEE x 34234234234