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:
{70737809-852C-4A03-9E22-2CECEA5B9BFA}]”

Cause
This issue is still under investigation.

Workaround
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