help, help, mysterious problem

please help me, whenever my character goes to a certain part of a level
he begins to go upward as if there were invisible stairs but, there aren’t!
He just begun doing this all of a sudden why :-?
I will email you the .blend if you want

edit:problem fixed

Take a look of some screenshots from my game Blazer
http://user1.7host.com/lagan/projects.html

Hah problem fixed! 8) it seems there was a renegade plane with an
evil ipo! :smiley: