More:

Browsing C:\Archivos de programa\ (Is the spanish one for "Program Files") console says:

C:\Archivos de programa\ empty directory

In Windows browser that folder has all the program folders inside but in Blender is empty and there is a folder labeled "Program Files" that has all the contents "Archivos de programa" should have. I'm pretty sure that it is a folder link problem in Windows Vista (maybe also W7).

Also a normal folder with spaces can be browsed normally.

Note: I tested this on Mac OS X 10.5.8 and it has no problems here, I can see folders with spaces, and other folders inside them, just fine.

Maybe sounds like something specific to windows/international localisation?

That's right Matt, this has nothing to do with spaces. Further investigation led me to the conclusion that this has to do with "Junctions" or "Reparse Points" in Windows. Those can behave like soft links and you can check whether a folder is a Reparse Point in code with:

if (GetFileAttributes(dirname) & FILE_ATTRIBUTE_REPARSE_POINT){

(Works in winstuff.c)

Although i couldn't manage to get the referenced path yet (to use it to show the contents). The answer maybe the GetFinalPathNameByHandle() Windows API method but i can't get it to work yet.

Can the title/description of the bug be changed to show the real info?

Uploaded a possible fix:

https://projects.blender.org/tracker/index.php?func=detail&aid=21952&group_id=9&atid=127

Confirmed, the reason are the newly introduced 'Junction Points' in Vista. These are used to map previously introduced folders (such as AppData or 'Program Files') as symbolic links that are by default hidden to the user.

The proposed solution works for Windows Vista but breaks blender on Win XP and older, still looking into a solution.

Moving to our todo list on wiki: http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Simple_Todos#Filebrowser