Like another user on the forum, I had problems with my FTDI cable and I couldn't program my Arduino at all. It used to work flawlessly, but suddenly it stopped working all together. It's recognised by the computer and by the Arduino IDE, but whenever I try to upload a sketch it displays the "not in sync" message. However, it works if I plug the FTDI cable into the computer, then click upload, and at the very moment when the IDE displays the sketch's memory info I plug the cable to the Arduino.
Hope this helps