SOLVED
The problem is not in my laptop but in version 1.4.4.4 of Dashboard.
Since a prior version is not available here, I searched the web for “Dashboard 1.4.3” Despite the many sites that show up in the search listings but actually provide ver 1.4.4.4, I managed to find at least one site providing a direct full download --that is, without receiving a downloader of that site, which then is supposed to download what you want and try to put some crapware in the machine-- of ver 1.4.3. It passed three different malware scans, so I installed it and now Dashboard actually shows the performance graph. I have blocked Dashboard at the Firewall so it does not update to 1.4.4.4.
SanDisk should reconsider its policy of not providing downloads for at least a prior-to-current version.
