Good to know mgarcia! Is there any way to unregister a device before you hard reset?
Yeah, in the Zune software - Settings > Account > Devices and Computers (or something along those lines)
You can only remove one device a month though, so if your queue of devices is full, you can only do a hard reset once every 30 days and keep your Zune subsciption active.
Example - I reset my Focus in January not thinking about this process.. this filled my device queue up without me noticing. About 3 weeks later, I purchased a micro SD card for it, which requires a full reset to initialize it. Since my device queue was full, I couldn't tie my phone to my Zune account for about 10 days.
It's one of my top complaints with the Zune software..