I found that in Win7, going to [Task Manager\Processes] and selecting ArcGIScacheMgr.exe and ending that process (while exiting the application) fixes a problem like this. Doing this has also helped me overcome the problem of when a spatial join fails to finish (another weird problem). The quick fix that works specifically for this problem though is simply removing the geodatabase from the table of contents (layers menu) -- try re-exporting your data again after doing this.
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