It works for me, but my filenames are in utf-8.. what charset is the
failing dir in?

the charset of my dir is ISO-8859-15.

Hrm, no clue how to fix this one atm.. but I'll keep it open.

It's advisable for a lot of reasons to keep your filenames in utf8, so
I'd recommend that for now you rename your folder..

Adding some information ... 

g_utf8_validate does say broken filename strings are correct, but gtk
bombs when trying to display them. Argh ... 

Changing summary, adding milestone ..

Here's a backtrace from 0.4.0:
[goetz@klama goetz]$ muine
INFO ( 7608: 0) Initializing GStreamer Core Library version 0.6.4
INFO ( 7608: 0) CPU features: (03020101) MMX SSE
INFO ( 7608: 0) registry: loaded global_registry in 0,160711 seconds
          (/var/cache/gstreamer-0.6/registry.xml)
DEBUG: gstgconf: error parsing pipeline osssink
No such element osssink
 
** (muine:7608): WARNING **: No GConf default audio sink key and
osssink doesn't work
 
(muine:7608): GConf-CRITICAL **: file gconf-value.c: line 68
(gconf_value_new): assertion `GCONF_VALUE_TYPE_VALID(type)' failed
 
Unhandled Exception: System.NullReferenceException: A null value was
found where an object instance was required
in <0x00044> GConf.Value:Set (object,GConf.ValueType)
in <0x0003d> GConf.Value:Initialize (object,GConf.ValueType)
in <0x00053> GConf.Value:.ctor (object)
in <0x0002f> GConf.ClientBase:Set (string,object)
in <0x00208> .PlaylistWindow:HandleImportFolderCommand
(object,System.EventArgs)in <0x0005a> (wrapper delegate-invoke)
System.MulticastDelegate:invoke_void_object_EventArgs
(object,System.EventArgs)
in <0x0012b> GtkSharp.voidObjectSignal:voidObjectCallback (intptr,int)
in <0x00030> (wrapper native-to-managed)
GtkSharp.voidObjectSignal:voidObjectCallback (intptr,int)

*** Bug 135240 has been marked as a duplicate of this bug. ***

I can't reproduce this anymore using the latest Mono and Muine - please reopen
(including version details) if you still see this.

Non-UTF-8 still does not work:

[goetz@virgo 2007.1 ~]$ export MONO_EXTERNAL_ENCODINGS=ISO-8859-15
[goetz@virgo 2007.1 ~]$ muine
inotify_add_watch: Datei oder Verzeichnis nicht gefunden
Fehler beim Laden des Plugins InotifyPlugin.dll: Attempt to watch /home/users/goetz/Music/Götz failed!

[goetz@virgo 2007.1 ~]$ locale
LANG=de_DE
LC_CTYPE=de_DE
LC_NUMERIC=de_DE
LC_TIME=de_DE
LC_COLLATE=de_DE
LC_MONETARY=de_DE
LC_MESSAGES=de_DE
LC_PAPER=de_DE
LC_NAME=de_DE
LC_ADDRESS=de_DE
LC_TELEPHONE=de_DE
LC_MEASUREMENT=de_DE
LC_IDENTIFICATION=de_DE
LC_ALL=

Lowering severity. Modern systems should use UTF-8 anyway.

muine development has been stalled and it has been unmaintained for a few years now. Maintainers don't have future development plan so i am closing all the bugs as WONTFIX. Please feel free to reopen the bugs in future if anyone takes the responsibility for active development.