I recently had this problem when wiping my phone then installing a new official 9000 OS.
Open DM
go to:
> 'Add/remove Applications'
> 'start' (click)
> ... 'task in progress'
> (if message to upgrade app loader ... then say 'yes' and follow instruction)
> ... 'searching for available device software'
> On the list find 'Documents to Go'
> Check off 'Documents to Go' and click 'next' to install
If you can not find D2G on the list then you can use the CD that came with the phone to install the first OS.
This CD has D2G on it.
First BACK UP your apps and data.
After, upgrade to the latest OS.