I can't install fonts in Windows XP Pro

Font folder looks and works like a normal, user folder.

Things I tryed so far without success while logged in with Administrator privileges:
http://support.microsoft.com/kb/314960
NO "install new font" in the files menu.

Drag and drop don't work as intended. The fonts are placed in the font folder but NOT installed. It used to install fonts. It's the method that I usualy use.

Sellecting fonts and using the "Send to..." option.

The repair option from TeweakUI "Power toy" don't work.

There is a desktop.ini file in the folder. It's content is:
[.ShellClassInfo]
UICLSID={BD84B380-8CA2-1069-AB1D-08000948F534}

In the registry, there are coresponding key.
HKCR\CLSID\{BD84B380-8CA2-1069-AB1D-08000948F534}
It's value is default with a value of "Fonts".

HKCU\Software\Microsoft\Windows\CurrentVersion\Shell Extentions\Cached\{BD84B380-8CA2-1069-AB1D-08000948F534} {0000010B-0000-0000-C000-000000000046} 0x401with a value of "01 00 00 00 33 00 32 00 68 8b b6 a4 cb 01"

There are also a few IconHandler keys.

Alain Martel, April 2011

I just found the problem:

My desktop.ini file was there, hiden and read only, BUT did not have the SYSTEM attribute.
It needs to be hiden AND system to work.

If you have the same problem, open the command line, navigate to your font folder.

There, enter this line:
attrib desktop.ini +s +h

Alain Martel, April 2011