How normal are the 360 unreadable disk errors?

[Americanidle]

I had one earlier today after about 2 hours of Burnout and then another a little bit ago after an hour of Burnout. I'm not playing any other retail games to test out anything else at this point but the Burnout DVD looks fine. I got my 360 in February so it's not one of the original "buggy" units. I also bought the extended warranty so i'm not worried about anything with that. I'm just wondering if these types of errors are being experienced by a good number of you or if it's a sign that I will be shipping mine in to MS soon.
Also on that topic, I assume if you send one in for repair, that you can just login and retrieve your profile on the new unit? You don't lose anything there correct?

[disarm]

for what it's worth, i have yet to see a disc error in the three months i've owned my 360, and i could count the lockups on one hand.  mine's been damn near perfect so far, and it's one of the original units (built on 11/6).  it shouldn't be an issue with Burnout either unless you happened to get a faulty disc.  i've logged a ridiculous number of hours in that game already without a single fault...fantastic game

if you do send your unit to MS, you will be able to retrieve your profile...but you'll lose any stored game data/saves that are on the HD if it's sent with the rest of the system.

[Zarkon]

I've had a DDE on a less than one -week old 360, while playing Oblivion...and talking to Lockdown.  Must be his fault.

[Misguided]

Never seen one on mine, but have seen discs give people trouble at the store.

[The Grue]

I have only ever had them in Oblivion.  I had 2 in one night and then I had one last night.  Never had them on any other game and I have had my 360 for months.

[Purge]

never for me

[Lee]

If you saw the thread I started yesterday on this, you know I am too.

Tells me to clean the disk. Only had errors in Oblivion and Burnout, but those are the only games I have played for hours at once sitting too.