Help - error entering data into cell
 

I have a shared, protected workbook.

When some users put data in cell E17 and click on the down arrow the cell
then shows ( jdjdjjd+E18) with the flickering border around cell E18 as if it
wants you to enter a formula or something.

They can input the same data and, by using their cursor, click in another
cell and this doesn't happen.

I can't recreate it as it doesn't do it on my computer.

Any ideas as to why this is happening?