Mobile Disconnected Mode

I am struggling to get offline mode working for a number of my clients. WSM Version is 3.6.0.
Normal Network streaming is working fine, and the process af Disk Provisioning to local disk is working fine. But when the clients boots, is says:
- Booting to Provisioned Hard Disk

Invalid Boot Sector.

I have tried different images, different image modes, and different client devices. Tried English versions of Xp and Win 7, same result.

Help anyone ?
V.A