1. Quit iTunes.
2. Navigate to where iTunes.exe resides on the hard disk:
\Program Files\iTunes
or
\Program Files (x86)\iTunes
3. Right-click in the Address field at the top of the Windows Explorer window and choose Copy Address.
4. From the Windows Start menu, type cmd in the Search field and press Enter.
XP users will need to choose Run... from the Start menu, type cmd and press Enter
5. Type cd followed by a space (but don't press Enter)
6. Right-click in the window and choose Paste.
7. Press Enter.
8. Type this:
iTunes.exe /regserver
9. Press enter.
10. Open iTunes.

I always used this widget just to fetch lyrics and it seems to have started working again.

I'm using
6.6 iTunes Companion (downloaded from his website)
Vista Service Pack 2
iTunes 8.2.1.6

This widget is what is what i am looking for but it is not working properly on my system. it doesn't show neither the art nor the lyrics. i am using vista sp2, itunes 9, companion 6.6. what might be the problem?

@volkan: I'd guess that iTunes 9 is your problem. This widget (and another one I use) stopped working with iTunes 9.

Anyone know what changed and/or how to fix it? I'm willing to get under the hood and modify the code, but I don't know where to start...

@volkan: I found the solution to my problem: http://discussions.apple.com/thread.jspa?messageID=10176575

Hopefully that helps you (and others) too!