A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
This post is the first that I've seen that mentioned what I always see as the second half of the issue:
I would receive the infernal message, after which selection of cells or ranges wascompletely disabled. I remained able to edit the contents of a cell by double-clicking. -JWM16
For the record, when I saw this, I could select a cell in a different worksheet in the same workbook but not in the worksheet I was originally in. To be clear, when I say "cannot select a cell" I mean that clicking in a cell in the worksheet where the problem occurred does not result in the cell getting a highlighted border.
Based on JWM16's post, I disabled the only COM add-in that was enabled ("Acrobat PDFMaker Office COM Addin") and restarted Excel. I have seen the dialog once with no COM add-ins enabled but after this occurred, I was able to select a cell in the worksheet.
A single occurrence doesn't tell us much but this does suggest that the dialog and being unable to select a cell may be two separate issues.
--- update---
An hour later, I saw the original problem: pop up dialog box AND cannot select a cell in the worksheet. The only way I've been able to again select a range of cells is by restarting Excel. ugh!