Windows 7 Expertise Required

As a reminder, I have a Toshiba A665-S6086 laptop, purchased back in November 2010. It is running the Windows 7 Home Premium (64 bit) OS. Windows backup has been working fine, backing up to an external 1.5TB Western Digital USB drive… until this Sunday, when Backup failed with the error:

The system cannot find the file specified. (0x80070002)

I’ve looked at the Windows 7 knowledge base article: Scenario 1 or 2 as described in that article don’t seem to apply, as no file is mentioned. I’m not sure Scenario 3 applies either: That’s the error message, but the computer does not freeze.

Only three things have changed since the last successful Windows 7 backup:

  1. Last week’s Patch Tuesday installed the latest set of Windows 7 patches
  2. I installed a different PS/2 keyboard (but have since switched back to the old one… and backups are still failing).
  3. I used a new jump-stick drive for a few hours. Said drive loaded a USB driver, but did not install any software via autorun.

Any ideas on what I should look into to get backup running again?

Here’s some further background. The full event data from the event log is:

The system cannot find the file specified. (0x80070002)