While trying to view changes that I made to a file I get the following error:

I installed the latest TortoiseSVN 1.7.11, Build 23600 – 64 Bit , 2012/12/12 19:08:52
Restarted my computer. Ran “Clean up” on the folder in which this file is located. Still getting this error.
UPDATE: Opened tmp file in Notepad++. There are NULL characters added to the bottom of the file. I was able to fix the problem by removing these characters.

Not sure how the NUL characters got in the file(in main file not tmp). Removed NUL characters, checked it in. Then made a change to a file and did a diff and diff works.