Something strange is that it has several log config lines. Weird..
Thats because you added some code in the ispconfig configuration part which resultet in dupliacte lines as ispconfig tried to repair the configuration. You can remove the duplicate parts and do not add any code in the ispconfig section for your default vhost.
But this can not cause your problem. I guess that one of the web log files must be correupted, it contains the data for a single request splitted to more then one line or a similar problem.