The whole bug story is avail. at http://bugs.debian.org/431696.
Basically, a segfault happened to our user when he tried to update a driver from a Windows client.
In the bug log, Jelmer Vernooij finally made the following analysis:
"We were freeing the files structure for the old file twice when opening the new file
He provided a patch that doesn't seem to be applied in 3.2.4 yet. I'll attach it here.
Created attachment 3684 [details]
Patch proposed by Jelmer Vernooij
This has already been added into the samba-3-2-test and samba-3-2-stable git branches, as well as master and 3.3.
Should be fixed in the next release.
Closing the bug according to Jeremy's comment. Please re-open if it's not fixed in 3.2.5 or 3.3.