from ESRI April 25th 2013
Critical information regarding Microsoft hotfix rollup and ArcGIS
If you have applied Microsoft hotfix roll-up KB 2775511 and created file geodatabases on a shared network location from a Windows 7 SP1 or a Windows 2008 R2 SP1 machine, your file geodatabases are unusable. You will see an error message referencing the item type when you create new datasets or items in a file geodatabase.
For example, the following message will appear when creating a new feature class:
“Failed to create feature class.
The item was not found. [ItemType:
This issue is still under investigation.
Esri is working on a patch to mitigate this issue. There are currently several workarounds.
See Esri Knowledge Base article 41119 for further information and updates