Well, this happened with my D1, now it's also happening with the Droid 2.
I have a habit of rebooting my phone daily. I don't know why, but I do.
I have two custom sound files on the phone, Specifically the SD card. For reference, they are:
GMail Alert: threat_detected.mp3
My issue is this: Sometimes, when I turn the phone on, I get an SD card alert. I shouldn't, seeing as how the "SD Card Notifications" option is turned OFF.
Before I turned it off, however (to combat the issue), I heard an odd tone from the phone. It sounded more like an alert tone rather than the sound I had setup. This happened about 25% of the time.
Also, I noticed that sometimes, upon receiving text messages or e-mails, the phone would play MUSIC files, for example, Sevendust's "Separate", instead of the notification sound scan_complete.mp3
This still happens quite often, I have to go into the phone settings and re-select my applicable sound files for the proper notifications.
On a side note, my phone still gives me the vibrations for SD notifications - i would much prefer this be turned off, but I can't figure it out.
Edit: On another note - it likes to vibrate ONLY even when I have it set to full volume across the board. I double check the settings too - the notifications are selected.
I do not want to have to root the phone to fix these issues.