HTC have support information for the Nexus One, please visit this page if you require OFFICIAL support for your phone from the manufacturer:
HTC - Nexus One Support and Repair
Google Phone Support
http://google.com/support/android/bin/request.py?contact_type=contact_policy
Live phone support is available at 888-48NEXUS(63987) and it works from 07:00am to 10:00pm PST;
Google Online Troubleshooter:
Nexus One Help
HTC Email Support
HTC - Nexus One Support and Repair
HTC Phone Support
