I ran Picard using the 1.2 source code with python 2.7 32 bit.
To get it running I had to compile astrcmp, and did so using visual studio 2012 Express under windows 8. Compilation was succesful and Picard ran succesfully as well. But using the program led to unexpected behavior.
Closer inspection revealed that the similarity2 function returned values larger than 1.0 (much larger than 1.0), which was because astrcmp returned very large values. This makes the color and icon assignment functions go out of bounds after performing a scan operation on a file.

I did not look into why astrcmp returns large values but rather resolved the issue by using the astrcmp.pyd file that came with the binary release. It might be an issue with 32 bit vs 64 bit (using a 64bit compiled astrcmp with a 32 bit python) but I'm not sure how to verify this.

Note! astrcmp does not consistently return very large values. From what I've seen, when the strings are equal it seems there is no problem. Only certain control paths return the large value. Might have something to do when len(b) > len(a), not sure about this though.

Feel free to contact me if you would like me to try out some things to resolve this issue.