Q: My Lighting Effects presets are gone, and I can´t save my own presets either (PS7 reported).
A: This problem seems to be connected with Windows XP´s Indexing Service, in particular, when this service is turned OFF.
By default, the indexing service is turned ON when installing the WinXP OS, but many people turn it off, because indexing will slow disk operations.
However, it has been reported that the problem with Lighting Effects presets are resolved when re-enabling indexing for the Lighting Styles folder.
How to check your disk indexing: In Explorer, find the folder in which Photoshop is installed, then find the subfolder Plugins>Filters>Lighting Styles. Right-click this folder, and choose Properties. Under the General tab, click Advanced, then check the box that says 'Index this folder for faster search' (or similar).
Reboot and check your Lighting Presets in Photoshop.