Within the last week my Z1 has started to boot excruciatingly slow. It never actually freezes, and will eventually end up in the UI, so I don't think it's the same problem that others have been having.

But whereas before it would take maybe a minute from when I turned on the car until I was at the disclaimer screen, now it takes close to five minutes.

I haven't tried a reset yet for fear of wiping out all of my contacts, but I will if that will help.

Has anyone encountered this before?

Nope. I would try the freeze fix just in case. Can't hurt anything and if it doesn't work you know you have a HD problem

Okay, I'll try that fix and see what happens.

If you can pull out the Hard Drive and scan it for bad sectors. Could be a bad hard drive.

When I've disconnected my battery to do other work, sometime my Z1 will boot up slowly until I reset it. Unfortunately I don't have the bluetooth module, so I can't tell you if you'll loose all your contacts. I know I didn't loose my radio and xm presets if that helps. Good luck