Hi,
Peter described several possibilities, but I think that your problem may be
quite simple. You may be accidentally resting a finger on Ctrl or also
touching Ctrl when you type '. When you press Ctrl together with ', nothing
should happen, but when you press it again, a single closing quotation mark
(’) should appear. If you press Ctrl+' and then press a letter, the letter
will be accented with accute if the letter + acute combination is available.
Ctrl+: works similarly and will add a diaresis (¨) to next letter typed, if
the combination is available.
Ctrl+` will produce a single opening quation mark if pressed twice and will
add a grave to next letter typed, if the combination is available.
Ctrl+^ will add a circumflex (^) to next letter typed, if the combination is
available.
Ctrl+~ will add a tilde (˜) to next letter typed, if the combination is
available.
Ctrl+, will add a cedilla to next letter typed, if the combination is
available.
Ctrl+/ will add a stroke to next letter typed, if the combination is
available.
Ctrl+@ will add a ring (°) to next letter typed, if the combination is
available.