What theme are you using? I doubt that it is a theme issue but it might be. You also might want to download a copy of your html file where you get the error, and check to see if there are any more errors that have been inserted in the html coding, sometimes that happens instead of the error being displayed.

Turning debugging on for the other lines didn't do anything? Hmmm... that is where it should be turned on for sql layers.

You are using 6.0 right? None of your blocks or anything else is for 6.5 or higher?

When you say that you posted something, you posted it where exactly?

Any chance you can either post a link or send it to me in PM so I can see the error and where it is displayed on the page please.