I'm apologizing beforehand for my lack of knowledge about Vegas Pro and computers in general.
I've been using Vegas Pro for years and have updated the program all the way up to date (Vegas Pro 23). Recently despite changing absolutely nothing, all the sudden my video preview has been having all sorts of issues that are also showing up when I go to render my video. I make very simple 1080p YouTube videos so it's nothing power hungry at all. I have tried changing several preferences, settings and formats but I still haven't been able to fix the issues. At this point I'm not sure if it's a computer issue or a Vegas issue, I've been using this same computer for 6 years with no problems.
What's happening is when I go play a clip, it will show it normally in the preview for the first couple seconds before showing a completely different portion of the same clip. Sometimes going back to the beginning will fix it and allow it to play and render normally but it almost always happens when I'm cutting clips up.