I would suggest trying a battery pull reset. Power down your phone... after it's completely shut down.. open the back and pull the battery out for a few seconds.
Replace the battery and back and power back up. This "hard" reboot will often fix problems like you are experiencing.
figured it out! i had the same problem with my new Sensations 4G (so its not just you...)
simply go to Settings>Applications>Manage Applications>Move to phone/SD
To fix it, just kill the launcher:
Settings/Applications/Manage Applications/(your launcher)/Force stop.
Also, you should "clear defaults" (on that same page).
Close the settings app.
Clicking the HOME button should ask what launcher to use.
Choose the one you prefer/installed
No problem. Glad you got it fixed. Enjoy the device.That worked. It was some issue with Nova launcher. When I forced stopped it and cleared the cache etc it worked. (Sorry before I kept force stopping the default Android launcher because I forgot I was using Nova). Thanks for your help!