Latest version is 7.23... https://www.nchsoftware.com/videopad/versions.html
For licensed users upgrades are free for up to six months. After that, VP will continue to fully function but a fee will be required in order to register the newest.
If you prefer to stick with 6.26, Clear Unused Cache Files, under OPTIONS|DISK tab. If that doesn't help try an UNinstall, then reinstall. Look here... https://www.nchsoftware.com/videopad/kb/1772.html
To see if something in the project itself is causing the fault, share it. Here's how... http://nch.invisionzone.com/topic/23659-tips-for-getting-help-on-this-forum/
Be sure to save it as a PORTABLE project, then zip it, upload and share the link here. Someone will check it out.