FYI, from Microsoft support site:
A recent, isolated issue was discovered in the SharePoint 2010 Products April 2012 Cumulative Update that could result in an HTTP 500 error when users delete objects to include documents, lists, and Webs and a new object is created using the same path where the original object remains in the Recycle Bin. This issue has been resolved in the revised packages. The revised packages include support for resolving issues related to the originally published updates.
thanks for this post
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