Give this a try and report back.
Close the program. Restart it, and before loading the project click OPTIONS | DISK tab and Clear Unused Cache Files.
If that doesn't help, again close the program and have its installer on hand. Delete all files in the following PC folders...
. "C:\Users\<your name>\AppData\Roaming\NCH Software\Components"
"C:\Program Files (x86)\NCH Software\Components" Alternatively, the files may be in "C:\Program Files\NCH Software\Components"
Reinstall Videopad. You might also test the latest version. For licensed users upgrades are free for up to six months from purchase date. After that, VP will continue to fully function but a fee will be required in order to register the newest. Retain your old install file and registration info.