My netbook suddenly began typing symbols while I was typing in Microsoft 7. How do I fix this in Windows XP?

Did you accidentally change the font? It doesn't seem to have effected any of your other typing, so that seems the most logical explanation.

Office 7?

"Ctrl + D"

That will bring up the font window.

Make sure all the boxes are unchecked, and the font is something you recognize i.e.. Times New Roman, Arial... what ever.