You reinstalled VP, then used the Revo uninstaller?
Did you use Windows Explorer (file manager) to locate "C:\Program Files (x86)\NCH Software\Videopad\Videopad.exe" -extfind ExpressZip "%L"? Delete it.
Seems as if the Sims launcher has been inadvertently associated with VP. You might try to reinstall the Sims 3 app.
Also click the Windows Notification icon (far-bottom-right of the desktop), then ALL SETTINGS. In the search box type "assoc" (no quotes). Click on Choose a Default App for Each File type. Review the types that are associated with Videopad. If it looks like one should instead be associated with Sims change its association from Videopad to Sims, if that choice is presented.