Examine Geometry - Data Structures Fail

Hi,

I am passing all the examine geometry tests but the "Data structures", where I get the following error:

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The object data structure is corrupt

Please undo last operation and check again 

Undoing fixes nothing, but I do not know how severe is the error or how could I fix it.

Any suggestion? What can cause this error? The documentation of "Data structures in Examine geometry" is quite brief.

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Data Structures

This function checks each selected body for data structure problems, such as corruption. The results are reported in the Information window. To highlight the invalid bodies in the graphics window, click the Data Structures option on the Highlight Results dialog.

Note: Any data structure error is cause for concern. The offending entities should be closely examine, then either repaired or deleted and reconstructed.