WDM Workgroup error when pushing image

I am trying to deploy a custom image to several D90Q7 clients. Merlin always fails with the error message: "Try 1:Merlin-Process-FAILURE [Fri Oct 11 15:00:32 2013][ERROR: Error while uploading MBR file. Http Error code : .][ERROR STAGE: MBR validation.][REASON: Flash is corrupted or improper repository/network configuration.][SOLUTION: Disable anonymous authentication if enabled on software repository under MyWDM virtual directory or check the device flash.]”

I have disabled anonymous authentication for MyWDM and tried a bunch of other things but no dice.

I would appreciate any help anyone here can offer.