push fails -- temporary sha1, no such file / corruptiion ???

i have a "centralized" bare repository, and 2 local clones. i make changes on the local clones and push the changes (to origin). i'm using ssh as my transport. this has been working for about a year, but i don't make frequent commits

today i tried to push to origin (from both a remote machine, and the machine on which the central repo lives), and the push failed:

-------------------------------------------------------------------------------------------------------------------------------- # git push Counting objects: 3, done. Compressing objects: 100% (2/2), done. error: unable to create temporary sha1 filename ./objects/2f: No such file or directory

fatal: failed to write object
Writing objects: 100% (2/2), 260 bytes, done.
Total 2 (delta 1), reused 0 (delta 0)
error: unpack failed: unpacker exited with error code
To /home/*****/repos/git/home.git
 ! [remote rejected] master -> master (n/a (unpacker error))
error: failed to push some refs to '/home/*******/repos/git/home.git'
--------------------------------------------------------------------------------------------------------------------------------

the "object/2f" varies with attempts to push from different remote repos, but it's always an "object/??". multiple attempts to push from the same remote repo always results in the same "object/??"

git version 1.6.0.4 ubuntu 9.04 (jaunty) amd64

"git fsck --full" doesn't return any errors for either the remote or the central repos. a fresh clone of the central repo results in the same error when i attempt to push. cloning the remote repos works, and pushes succeed. i did a /forcefsck and didn't see any errors (but also couldn't find any real logs - hidden by the splash screen i guess)

i'm not sure which version of git was used to create the repository, but it was probably 1.5.4 (ie, ubuntu hardy). incidentally, i have another repository "triplet" that i use for a different set of code that is working fine, that was created and used with the same machines/toolchains/versions

any idea what is going wrong ???