Cannot remove line on spreadsheet

[pivotowski]

I am puzzled by a thin black line (that looks like a border line) on a spreadsheet that I am unable to remove, whatever I do. It starts halfway across column B and stops just at the end of column Z.
It is not a border line.
It is not a page break.
If I delete the rows it appears on it remains visible.
It is not an object floating on top of the spreadsheet.
Any ideas?
Thanks.

 

[TFCJamieFay]

Try: Window > Unfreeze Panes

HTH

Jay

 

[pivotowski]

It's not the freeze panes, I have the pane frozen towards the top of the sheet but this line is towards the bottom and moves up and down when I scroll.

 

[JimM]

Is it a hidden row / row with a very low height ??

 

[pivotowski]

JimM,
No I can confirm it's not a row with a very low row height.
There is something else a bit strange on this sheet - whenever I delete or insert rows I get an error msg "A formula in this worksheet contains one or more invalid references - verify that your formulas contain a valid path, workbook, range name and cell reference".
Not sure if this is relevant but I don't usually get that msg in other workbooks, even if there are errors on the sheet.
pivotowski