Auto pasting when it's not wanted.

Hello,

I have been working in a few different excel spreadsheets recently and have noticed that text is being automatically entered into cells that I don't want it in and is erasing what was previously entered into that cell. For example text from cell Q-100 is going into cells R-60 to R-120. I don't know how to stop this from happening and it's causing me to have to go back and restart my work. Can anyone please help me?

Maybe some sort of Macro is causing trouble? Maybe??