The old install file is the one you used to install Videopad. It's usually stored in "C:\Program Files (x86)\NCH Software\VideoPad"
Newer versions can always be test driven without licensing, but they will replace your dated 7.39. Later, you can either revert or upgrade. 7.39 is available here. What was your purchase date? A newer version, within the free upgrade window, may be available. That could be the fix.
The registration code was mailed at purchase. If necessary to re-register, click the MENU icon at the top-left of the window, then the Register Videopad item.
If you share it, someone here will run and export your project with the latest version and report results.
The process is easy, quick and can be done privately. Just follow these steps...
Back up --- With your project on the timeline, click on MENU at the top-left. Click FILE|BACK UP PROJECT FILES TO FOLDER. Choose a folder and SELECT FOLDER.
Upload --- Use a free server - Google Drive, MS OneDrive, etc.* - to upload the saved, numbered FOLDER. Do NOT upload the individual VPJ or export file.
Get link --- Get a public link. If using Google Drive click GET SHAREABLE LINK. If necessary change "restricted" to "anyone with the link can view"
Share --- Click COPY LINK | DONE. Paste that link here, or click the folder at the top-right of this forum to message it privately to me. It won't be shared.
* Before uploading, right-click the folder, click PROPERTIES. Look at the File Size to confirm that it's not too big for the free space on the server.