TortoiseSVN Icon Overlays Disappearing in Windows Explorer

We're using TortoiseSVN as a Subversion client for Windows and it's been great, but the icon overlays that appear in Windows Explorer have suddenly started to disappear. What's really strange is that they may appear at the top-most directory, but disappear when you drill down.

I haven't found the root cause yet, but here's how to get them back.

1. Open the Task Manager. Find TSVNCache.exe and click End Process.
2. Shutdown and then restart Windows Explorer. Go to Start > Shutdown. Hold down the Shift+Alt keys and then click the Cancel button. To bring up the Task Manager, hold down the Ctrl+Shift keys and then click Esc. Now, in the Task Manager, go to File > New Task and type in explorer.exe. Supposedly, this is the "proper" way to kill and restart the Windows Explorer process.

Others have reported similar problems. See http://svn.haxx.se/tsvn/archive-2007-01/0190.shtml for one example.

UPDATE: In XP Pro, all I needed to do was end TSVNCache.exe and then I could refresh Windows Explorer and the overlays came back.