First thing: Under OPTIONS | DISK tab, Clear Unused Cache Files prior to loading projects for the first time. If currently working on a project the cache can be cleared at that time as well.
Of course. Save Project File AS routinely, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite. Then you can restore a project to the state it was in when saved. Just double-click the VPJ file (which isn't playable).
What version of VP is being used? Try this one. 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.
What are your export settings? The suggested defaults usually work well. What is the resolution of the bulk of the source files?
Share your project and someone will help. This is easy, quick and can be private. Issues are often quickly resolved. Just follow these steps...
1. 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.
2. Locate the saved, numbered folder. No need to upload the export or VPJ files. Upload it to a free server - Google Drive, MS OneDrive, etc.*
3. Get a shared, public link. If using Google Drive click GET SHAREABLE LINK. Click the blue "Change to anyone with the link..." Then click COPY LINK | DONE.
4. Paste that link here, or click the folder, above top-right in this forum, and message it to me. This is private and 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.