Keyboard typing problem

When typing in words and I press Shift and a letter for it to show that letter in Capital or Upper Case I seem to sometimes press Ctrl and a letter and then when I continue typing all sorts of strange letters show instead of the proper letters showing on the keyboard. If I am in a Word document I can close the Word program and then re-open the program and it types correctly. However tonight I was typing in a new email message in Outlook Express and even closing Outlook Express and re-opening did not solve this problem.
How can I reverse this mistake so that I do not have to re-start the computer to rectify the mistake.