Try launching git-cola from a bash shell and it should give you some
output in the event of an error.
e.g. run ..../path/to/pythonw.exe ..../path/to/git-cola
Is your git in the default location? If not, you'll need to specify
it to cola by creating a ~/.config/git-cola/git-bindir file with the
path to git's bin directory, e.g.:
C:/Tools/Git/bin
This is only needed if Git is not installed in the default location.
--
David