Nis 2011 after full scan are creating and left some files

Some trouble are occurring, after full system scan using NIS 2011 (18.1.0.37).

A few file with few bytes are left on %SystemDrive%.
These file are named by hexa code, into { name }.
Almost 6 to 8 files, per full scan.
News one are created after new full system scan.

 

Why that?

 

Why these files are not deleted, when finished?

 

Why this task spent a very long time on Win7-64, comparing with Win7-32?