Are you looking at (1) the unaltered raw data files as generated by Inquisit or (2) at files that have already been processed in some way (imported into some spreadsheet application, merged, etc.)?
If (1), could you please provide one or two data files that show those entries ("a", "zzz"). They have no meaning and should not be present in the data columns you mention.
If (2), those entries may have been mangled during import or processing. Double-check with the original raw data file and verify whether the issue exists in the unaltered file or only the processed one.