Windows XP automatically caches the chosen appearance of each folder, when the user browses through the folders. One can configure for how many local (ShellNoRoam) and network folders it will remember the customization with these DWORD values:

[HKEY_CURRENT_USER \Software \Microsoft \Windows \Shell]
BagMRU Size = 5000 (Default - 5000, XP SP1 - 200)

[HKEY_CURRENT_USER \Software \Microsoft \Windows \ShellNoRoam]
BagMRU Size = 5000 (Default - 5000, XP SP1 - 200)

One can clear the customization of all folders by deleting the following subkeys (Sometimes necessary if Windows stops remembering ones customizations):

[HKEY_CURRENT_USER \Software \Microsoft \Windows \Shell \Bags]
[HKEY_CURRENT_USER \Software \Microsoft \Windows \Shell \BagMRU]
[HKEY_CURRENT_USER \Software \Microsoft \Windows \ShellNoRoam \Bags]
[HKEY_CURRENT_USER \Software \Microsoft \Windows \ShellNoRoam \BagMRU]

Note to enable Custom folders one have enable the following option: Control Panel -> Folder Options -> "Remember each folder's view settings". It should be reflected in this DWORD registry value:

[HKEY_CURRENT_USER \Software \Microsoft \Windows \CurrentVersion \Explorer \Advanced]
ClassicViewState = 0 (0 = Remember Folder View, 1 = Don't remember)

More Info MS KB812003
More Info MS KB813711

Related Setting the default folder view for all folders
Related Configure caching of remote customized folders in WinXP

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