On some PCs, the 6.4.64 installer goes awry and does not properly update an existing installation.
Uninstall 6.4.64 and then install your previous version. Then uninstall your old version. Follow this with another install of 6.4.64. This usually takes care of the problem.
(The Picotologist) http://www.autonerdz.com
THE PicoScope Automotive Authority
In North America