All my unconverted leads get modified by my ID every night at Midnight somehow?

[JustinWilliams…]

Every night around midnight all our unconverted lead records seem to get touched by me.  I get listed as the last modified user.  In many cases certain values get changed.  I activiated  some field history tracking on key fields like phone, company , name, fax, etc.  It looks like leads are being revereted to some prior value.  I just started the tracking yesterday and reported on the history.  Indeed several examples show our reps making a change to a phone number, and at midnight I get logged as changing it back.

I am the admin so i am the default workflow user.  What is the best way to track down this automated mass lead update that happens every midnight?

[JustinWilliams…]

Detailed note, I don't see any timed workflow or scheduled jobs that fire once every day around midnight.  The only apex jobs are both hourly schedules, the rest are report and dashboard refreshes.

[JeffM]

To help figure it out, look at the Login History for the user responsible for the change (you in this case).  You can see it at the bottom of the Setup->Manage Users page for the user.  The login history will show the time, IP,and most importantly the "connection" being used (is it Browswer, Outlook, Partner API, SOAP API, etc).

[Rahul Sharma]

Seems, there is use some tool like scheduled command line data loader or something like that.
I agree with Jeff, Checking login history is best way of debugging.