really? then it may be a problem with an event or a PBS file. for example, calling a non existent trainer in an event (even though it's not autorun) on any map (even if it's not where the player starts or last saved at) can throw an error. So there may be a problem with an event on one of the maps. I'd say drag the maps one at a time out of the kit and somewhere else temporarily and see if removing any of them causes the error to stop.
You mean this one?
Message: cannot convert Regexp into Integer
It's a pretty odd problem. Do you know of any changes made prior to it doing that? I'm assuming that wasn't happening all along, so somewhere down the line it must have popped up. Although I'm also going to assume you don't test the battle system every time you make any little changes, since that'd be kind of excessive. So a change was probably made a while in advance of when the error actually popped up on screen, since you wouldn't have known something was wrong without testing the battle system. Was it right after the resolution change?