We have sql databases on server which are already subject to scheduled backups each evening as part of the database maintenance plan.
There are no other scheduled jobs on the server.
We do have an additional 2 databases which have been restored based upon the live backup and are not subject to any database maintenance plan nor part of scheduled jobs.
All of the databases on the server seem to be subject to additional backup action approximately every 24hrs (one day at 10:40am, following day at 11:04am et cetera).
The file created is on the c: drive - but it does not actually appear on the C: drive.
The backup file size is preceded by negative sign, e.g. -710038kb
The server log records the following message:
Database backed up: Database: TestCC, creation date(time): 2008/04/23(18:25:35), pages dumped: 1484006, first LSN: 131986:5746:1, last LSN: 131986:5751:1, number of dump devices: 1, device information: (FILE=1, TYPE=VIRTUAL_DEVICE: {'TestCC_00__55f49cd3_598f_42d4_aa41_cc36aca6f0e6_ '}).

The restore of dtabase works satisfactorily when the full backup is selected and the assoicated media family are then automatically selected (jumping/omitting these daily unwarranted backups).

Could it be a compression/shrinking of the db?
If I go to restore a db, the most recent'spurious backup' appears as the last full back up and the legitimate transaction logs below it - but it fails if trying to restore from this non-existant file (obviously).

Any experience of this anyone?