error: Excel encountered an error and had to remove some formatting to avoid corrupting the workbook

[Keith]

We have a workbook (company standardized on Excel2003) used by several
people every week to track operational data. In addition to the content
being updated weekly, we also change and update VBA code within the workbook
on a fairly regular basis. The most recent change was to copy target ranges
to a second worksheet and export the range as a GIF and auto-email those
images to folks who need to see that specific data.

Within the last 3 weeks or so, some folks have reported getting the error
"Excel encountered an error and had to remove some formatting to avoid
corrupting the workbook. Please recheck your formatting carefully."

I've never seen this error before, and I'm not sure what types of formatting
might cause problems for Excel. I've asked if anyone is copy/pasting HTML
into the document, but they report that everything is hand-typed in (plus
some text data files that are automatically downloaded weekly via VBA).

Is there any way to capture any information via VBA to detect what
formatting might be causing the problem so I can trace it back to it's
source?

Thanks,
Keith