query for recent changes that could lead to problems with gits index?

Hi,

some of my users have recently experienced strange problems with the
index since 1.7.0. It is msysgit on windows but seems to be more generic
to me. Unfortunately we were not able to reproduce the failures.

Problem 1: User experiences strange behavior with staging files. I was
puzzled until I found out that there was a double file entry in some
recent trees. git ls-tree showed something like this:

... fileA
... fileB
... treeA
... treeA
... treeB
..

and git gc complained about it. There where non-ascii filenames involved
in the changes.

Problem 2: Today a user asked me why a change he was only seeing in git
blame marked as "working tree" does not show up in git gui nor gitk.  A
restart of both tools did not help. I took a brief look was puzzled and
a 'git reset' resolved the issue. Unfortunately I did not take a look at
the output of git status.

My question: Does anyone know recent changes (or situations) that could
lead to such behavior?

cheers Heiko