check-mime-type, Windows client, non-ASCII path

Clients: Windows-XP, Windows 7, svn 1.6.16 (Spanish)
Server: Linux (CentOS), svn 1.6.16 (Spanish)

Repository created OK
Hundreds of revisions already checked-in OK
Hook "check-mime-type" (bash) added in server
A couple of revisions checked-in OK
New file added with non-ASCII characters -> Problem:
Path name (in Windows, client): C:\Usuarios\arenero\Inútil.TXT
(note the u with an acute accent: ú)

C:\Usuarios\arenero>svn ci acentos -m "Prueba 1"
Adding acentos
Adding acentos\In£til.TXT
Transmitting file data .svn: Commit failed (details follow):
svn: Commit blocked by pre-commit hook (exit code 1) with output:
/opt/csvn/data/repositories/telecontrol/hooks/check-mime-type:
`/opt/csvn/bin/sv
nlook proplist /opt/csvn/data/repositories/arenero -t 44-1e --verbose
acentos/In
?\195?\186til.TXT' failed with this output:
svnlook: Path 'acentos/In?\195?\186til.TXT' does not exist

To help diagnose it, I tried to check out an already existing file with
accents in its name
(checked in before the Hook "check-mime-type" (bash) was added in the
server).
Check out fails.
Oh, my God.

Suggestions ?

-- 
Ignacio Gonzalez T.