Problems printing hollow objects

I’m using a TAZ5 at the library. Whenever I try to print an object that is hollow it won’t print. What happens is the printer homes itself (at the front corner) then moves to the center of the bed, but as it moves from the home position to the center of the bed it gradually rises so that when it gets to the center of the bed its about an inch or so above the bed and then it starts to print. Any ideas why it does this? Has anyone else seen this?

Thanks,
Jim

This sounds like a file error. Could you post a copy of the .stl you are trying to print?