System Center Data Protection Manager: Error when lowering the allocated storage
Yesterday I was working on a DPM installation and made a mistake when I was working on a protection group and I needed to change the size of the allocated storage. I made the mistake by lowering the size and pressing the TAB button and suddenly the DPM console crashed. Here’s what I did:
Go to the DPM Console –> Protection.
Choose the correct protection group and press the Modify Allocation button.
Press the Calculate button
After this, I changed the size of the replica to 10 GB and pressed the tab key.
Et voila,

Till now, this bug is confirmed by Microsoft and not yet solved… ;-)
http://support.microsoft.com/kb/973677