CaMeRuSh,
Your error is generic, but is many times related to a problem entity or segment, usually a custom one.
Load one of the included levels into the editor, save and then build it. If it builds normally, then your program is working and the problem is in your new level.
If that is the case, you will have to try to work backwards, removing what you inserted until the level will build and you find the problem entity or segment.
If the included levels error as well, then your program has been corrupted and must be repaired/reinstalled.
Good luck.
Best.
