Inconsistent UIDS and wiping a data partition I've inherited my wife's Android phone (GT540) when she got a newer, shining one :-)
We think to  have factory reset it (via the privacy option), and in fact it has finally stopped to refer to her account and all the pics are gone. But I keep getting a warning message, about inconsistent UIDs and the need of wiping the data partition to be sure.
I can click on the only button &quot;I am feeling lucky&quot; to continue, without noticing particular issues.
Obviously, as per Murphy, the message is not popping up right now, so I can't copy it verbatim :-) Will edit the question when it comes out again.

EDIT
The precise message is:

System UIDs inconsistent
UIDs on the system are inconsistent, you need to wipe your data partition or your device will be unstable.

And it is followed by the unexpected crash of the Market application (processocom.android.vending).
So:

what is happening? what data partition is actually worrying it? Wasn't the reset &quot;hard enough&quot;?
what could happen, what UIDs is it referring to?
how can I fix it?

I have a new SD card, which is as far as I can tell empty. I would have liked to format it before using it, but the option is not available: I can only unmount it. Is this (missed) formatting the required wiping to reset the UIDs? Or is it a completely different thing, which I will search/ask in a later question?
Being new to the Android system I don't know if any other info are missing. The kernel is 2.6.29 (but I would be surprised if such basic matters were strongly dependent on the precise kernel version....). Just in case the firmware of the phone is 2.1-update1.

UPDATE
I have asked my wife and she actually did the factory reset suggested. Just in case I did it again, and we still get the error. What now?
I found another solution:

Have a look at /data/system/uiderrors.txt. There you will find the apps that are responsible for the trouble. You can delete them (manualy if necessary) to fix the issue. Reinstalling the apps brings the error back, though.