Dmetrey,
What operating system are you using?
If this is Windows Vista or Windows 7, you need to install and run the program as an Administrator. This allows Trainz and Content Manager to read and write files properly.
The database crashing issues is commonly caused by turning off or restarting your computer too soon after shutting down Trainz or Content Manager. The way around this is to wait perhaps 5 or 10 minutes before performing either of these actions. The reason behind this is there are still files open in the database after the program has been closed. When restarting your computer, you are actually corrupting the files, and causing file damage and problems later on when you try to start the program again.
So now that you've probably corrupted the files again, try a Extended Database Repair. Let the program run overnight because this can take some time. Tomorrow install the latest patch to bring your program up-to-date, and let the program run a DB repair as well. It is important that you let the patching process complete because by exiting, because you think the program was stuck, will cause problems such as those you are seeing here. In addition the program its self will want to run a DB repair after patching. Let it do its thing otherwise you will be in a mess as well.
John