The problem either was not resolved - still in the process or was dropped. Or the criminal history is not up to date - the agency has not updated the outcome to the federal government or state depending on what scope your background on i.e. local or nationwide.
Disposition refers to a judges final ruling. My best guess would be that 'no disposition' means that there was no final ruling. Not sure if that means that the ruling is pending or if it is, in fact, similar to 'nolo contendre'.
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