power source affecting my IR receiver
The datasheets of most IR receivers recommend some minimal filtering of the power supply, check for instance http://www.sharpsma.com/webfm_send/1351 p 4 : 47 Ohm / 47uF.

Even with such power filtering I have experienced that an IR receiver on one of my boards worked much better when powered from a wall-wart+7805 compared to being powered (directly) from USB.