By default, Explorer in XP will remember the customization settings for 400 folders. When you exceed that limit, it will no longer retain the settings. You can edit the registry to change that limit, or you can use the Bags8000.reg file from the Kelly's Korner web site to do it for you. You can download the file from this page: Click Here
It's number 2 in the left column, titled "Increase folder view size limit to 8000." To edit the registry yourself, do the following:
1. Open the registry editor.
2. Navigate to the following registry key HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ Shell. If this key is not present, skip to step 8.
3. If a subkey named BagMRU is present, delete the entire subkey.
4. If a subkey named Bags is present, delete the entire subkey.
5. Look for a value named BagMRU Size (with a space between BagMRU and Size).
6. If this value is not present, select New DWORD Value from the Edit menu and name the new value BagMRU Size.
7. Double-click on the BagMRU Size value, choose Decimal, and enter the desired number of folder settings for Win XP to remember (for example, 1,000).
8. Navigate to the Registry key HKEY_ CURRENT_USER \ Software \ Microsoft Windows \ ShellNoRoam. If present, repeat steps 3 through 7.