Git reproducible corruption errors on merge/checkout not detected by git fsck --full --strict

Hi all !

I use git regularly since twelve months; on one specific repository, I  
had repetitive "inflate: data stream error (incorrect data check)"  
errors. These errors appear when checking out from one branch to  
another or when merging; however doing a "git fsck --full --strict" on  
either the local repository or the remote repository before the  
operation does not show anything wrong.

The bare repository is located on a Mac OS X 10.5 PPC server with Git  
1.5.X.Y (X, Y not known), the local client is Git 1.6.6 installed  
through MacPorts. I am stuck with Git 1.6.6 due to the MacPorts  
architecture. Local zlib is 1.2.3_3.

I created a new local repository, reimported the files manually (only  
the files, losing all the history in the process), and errors happen  
again. The errors seems to appear when Git creates a local pack to  
store the object files.

I am now installing Macports git 1.6.6 on the server to do further  
testing.

My questions :

1) is "git fsck --full --strict" the most comprehensive check I can do  
on a repository ?
2) are there known bugs leading to data corruption in the git 1.6.6  
prerelease and/or zlib 1.2.3_3 ?
3) is there a verbose flag or a log I can consult (and eventually send  
to this list) ?

Kind regards,

Denis Rosset