red triangle in upper left of some cell

[Mike]

All of a sudden there are red triangle in the upper left
corner of the cells in some columns or rows. It will not
calculate a formula in these areas. What do they mean,
where do come from and how do I get ride of them

 

[Arvi Laanemets]

Hi

You have some comment about this cell made. 'Edit Comment' and 'Delete
Comment' from right-click dropdown menu can help you.

 

[Gord Dibben]

Mike

Upper Left corner triangle might indicate Error Checking enabled with Red as
color of indicator.

When you select the cell do you get an exclamation mark with a little
drop-down box with options?

Gord Dibben Excel MVP