I feel like I probably shouldn't say this, but I'm going to.
Software is complex. Software which was originally written approx 20+ years ago is a absolute nightmare to maintain. There will _always_ be bugs (which is why forums like this can help pick them out, and ultimately report back to Apple - whether they choose to address them or not is out of our control) and there will always be corruptions of user files; this is computers. And the more complex the program, the more potential there is for bugs and corruptions.
This is a community of users, mostly very experienced users who have used this software for many, many years, possibly like yourself Frankenhaus! Some of us experience problems others have also experienced; other folks discover issues no-one else has ever come across, usually as a product of their workflow and the ways they choose to satisfy their creative urges. Your problem appears to come under the latter.
If you're not willing to accept the investigations, workarounds or solutions provided here, it's difficult to know what you actually want. David's suggestion of deleting all the tracks apart from the problem tracks is very reasonable, and something some of us do as normal practice in order to diagnose a problem. Elimination of extraneous stuff leaving only 'the problem' is often the easiest way to work out what's gone wrong.
If you want to solve the problem, go down the same path we all have to go down when we're solving technical issues, which is what your issue is. You can be as angry as you want about the program, and your problem, but it won't fix itself.
Sorry, I had to say it. The folks here are trying to be helpful (and they _know_ this product) but your tone and language doesn't sound like you understand that. Or maybe you do and you're just having a bad day! 🙂