Word opening with one 'box' character, then crashing

[Katie]

Good Afternoon,

A co-worker is having a problem with her Word documents. When she opens a
new document, it displays an ASCII character that's a 'box' where the cursor
is. If she tries to delete this box, it crashes word.

I've checked to see if 'mark-up' is showing/hiding and it is hiding.
(Regardless, I have not seen this character used in formatting before.

Is anyone familiar with this problem?

Thank you in advance for your assistance,

Katie