I recently built a new home( just moved in last week). My harbor breeze fan has been working fine all week, all three fan speeds worked based on the button pressed on the remote. After last night however, no matter what speed button I pressed, the fan automatically switched to high speed. Any ideas on this? Thanks in advance!

Check your battery in your remote.

If batteries not the problem, try turning off circuit, wait maybe 20 seconds and turn back on, some electronics get "Confused" by spike or surge.

Sounds like the receiver is bad. On a fan this new, you should return it.

Ceiling fan remote controls - help and FAQ- Ceiling Fans N More (http://www.ceiling-fans-n-more.com/ceiling-fan-remote-controls.php)