I seem to be having a lot of the same problems as everyone else in regards to the 2.1 update. From what I've read, a HARD RESET may solve many of my issues. Can someone give me step-by-step instructions on how to do this? Also, I've read that you should back up all your files on to your computer. Some guidance here would be appreciated as well.
From your home screen press Menu > Settings > Privacy > Factory Data Reset.
Your contacts are already backed up to the email account you have registered with the device. So save any other files you may want - photos, documents, music. You can do this by selecting the Disk Drive option when plugging your device into a PC. Then just drag the files from the phone and drop them on to your desktop.
This did seem to solve all my issues I was experiencing...at least from what I noticed. However, not all my contacts were synced back up. It seems some of the contacts I initially deleted are now on the phone, and some of the contacts I have added in the last couple months are no longer there. Also, I wish I had written down all the apps I downloaded because they are all gone now. At least my calendar works though, that was my biggest issue since the upgrade.