Transparent text in Windows XP desktop icons.

I have always thought that desktop icons with a block of color behind the text looks ugly. So, I have always used a transparent block behind the text.
To achieve this in Windows XP never required anything more than ensuing that the "Use drop shadows for icon labels on the desktop" is checked in Control Panel>System>Advanced Tab>Settings button in Performance section>Visual Effects tab.
However, a day or two ago, my desktop icons suddenly adopted a non-transparent label for reasons I still don't understand.
Strangely, the drop shadows option, as described above, was indeed checked.
So, a little research was necessary.
Post #2 in this thread is very useful and points out that, in fact 4 conditions are necessary to ensure the icons have transparent labels as follows (copied direct from link):

1.Control Panel-System-Advanced-Performance Settings.
Check "Use drop shadows for icon labels on the desktop" on the Visual
Effects tab.

2.Right-click on Desktop - "Arrange Icons by" and ensure Lock Web
items is cleared.

3.Transparency will not work if you have web content on your desktop,
Control Panel - Display Properties - Desktop tab - Customize Desktop -
Web tab. Clear all check boxes.

4. Ensure the Wallpaper is an image file not HTML.

Funny thing is however, that my system complied with all four of these prerequisites.
Post #4 in this thread re-iterates that the Active Desktop must be disabled to allow the transparency of the icon labels (which is essentially Step 3 above.
The details provided are reproduced below:

Open the Control Panel.
Open the Display icon.
Click the Desktop tab.
Click the Customize Desktop button.
Click the Web tab in the Desktop Items window.
If you wish to enable the Active Desktop, check My Current Home Page. Add your current home page into your desktop or click New to add another web page and/or other Active Desktop features. To update the content, click the Synchronize button.

If you wish to disable Active Desktop, make sure all checkboxes in this window are un-checked.

However, once again, nothing was amiss in my system.
So, I ENABLED the Active Desktop as described in this link and immediately DISABLED it whereupon the icon labels became, much to my relief, transparent.
Unfortunately, I still have no explanation for what happened.