Changing GUID change program behaviour - c#-4.0

Question

I'm currently working on creating a namespace extension.
So I want to create an entry in Computer, and had explorer.exe calling my IShellFolder implementation.
I had it working for few minutes (I stupidly decided to clean up the code before commiting), so I'm somewhere near.
But I noticed something very strange: changing the GUID value of the Class change what I see in explorer.exe
I found that question which tells me I am not doing something bad
Here's the code:
AssemblyInfo.cs:
[assembly: ComVisible(false)]
[assembly: Guid("007C5100-4251-47BE-8141-D2AD3F496E6A")]
RootFolder.cs:
[ClassInterface(ClassInterfaceType.None)
[Guid("007C5101-4251-47BE-8141-D2AD3F496E6A"), ComVisible(true)]
public class RootFolder : IShellFolder, IShellFolder2, IPersistFolder, IPersistFolder2 {
private const String _mountPoint = "Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\MyComputer\\NameSpace\\{0}";
private const String _mountName = "CLSID\\{0}";
#region Shell Extension Registration
[ComRegisterFunction()]
public static void Register(Type t)
{
Console.WriteLine("Registering {0}...", t.GUID);
try {
if (t.GUID == null)
throw new ArgumentException("CLSID must not be null");
using (RegistryKey key = Registry.CurrentUser.CreateSubKey(String.Format(_mountPoint, t.GUID.ToString("B")))) {
key.SetValue(null, "RootFolder");
}
using (RegistryKey key = Registry.ClassesRoot.OpenSubKey(String.Format(_mountName, t.GUID.ToString("B")), true)) {
key.SetValue(null, "RootFolder");
using (RegistryKey shFolder = key.CreateSubKey("ShellFolder")) {
shFolder.SetValue("Attributes", 0x78000040);
shFolder.SetValue("WantsFORPARSING", "");
}
}
using (RegistryKey key = Registry.LocalMachine.CreateSubKey(#"Software\Microsoft\Windows\CurrentVersion\Shell Extensions\Approved")) {
key.SetValue(t.GUID.ToString("B"), "RootFolder");
}
IntPtr pidl = NativeMethod.SHGetKnownFolderIDList(KnownFolder.ComputerFolder.clsid, 0, IntPtr.Zero);
NativeMethod.SHChangeNotify(NativeMethod.FSNotification.UpdateDir, NativeMethod.ItemMeaning.IDList, pidl, IntPtr.Zero);
} catch (Exception ex) {
Logger.Write(Logger.Severity.Fatal, "Registration error: {0}", ex.Message);
throw; // Re-throw the exception
}
}
[ComUnregisterFunction()]
public static void Unregister(Type t)
{
try {
if (t.GUID == null)
throw new ArgumentException("CLSID must not be null");
Registry.CurrentUser.DeleteSubKey(String.Format(_mountPoint, t.GUID.ToString("B")), false);
using (RegistryKey k = Registry.ClassesRoot.OpenSubKey(String.Format(_mountName, t.GUID.ToString("B")), true)) {
if (k != null)
k.DeleteSubKey("ShellFolder");
}
using (RegistryKey key = Registry.LocalMachine.CreateSubKey(#"Software\Microsoft\Windows\CurrentVersion\Shell Extensions\Approved")) {
if (key != null)
key.DeleteValue(t.GUID.ToString("B"), false);
}
IntPtr pidl = NativeMethod.SHGetKnownFolderIDList(KnownFolder.ComputerFolder.clsid, 0, IntPtr.Zero);
NativeMethod.SHChangeNotify(NativeMethod.FSNotification.UpdateDir, NativeMethod.ItemMeaning.IDList, pidl, IntPtr.Zero);
} catch (Exception ex) {
Logger.Write(Logger.Severity.Critical, "Registration error: {0}", ex.Message);
throw; // Re-throw the exception
}
}
#endregion
#region IShellFolder2 Inheritance
[All the methods looks like that, this is just a test]
public IEnumIDList EnumObjects(IntPtr hwndOwner, EnumObject flags)
{
Logger.Write("Tracing....");
throw new NotImplementedException();
}
#endregion
#region IPersistFolder2 Inheritance
[Ditto]
#endregion
}
I use the range 007C5{100...120}-4251-47BE-8141-D2AD3F496E6A for my GUIDs
When my extension has GUID 007C5101, it just shows "RootFolder" without any attributes.
When it has 007C5100 (same as assembly), or 007C5102, or 007C5103, it is shown as "System Folder" (even though it doesnt call my DLL).
I'm a little puzzled by this behaviour, how in the world can changing a GUID lead to this change ?
Note: I ran a search through the registry for 4251-47BE-8141-D2AD3F496E6A (the immutable part of my GUID), and couldn't find anything after unregistration.