Assuming you have already tried different platen height settings, I agree with Michael that the problem is likely with your printer.
I also feel the need to point out that my own experience differs from both of the posters who claim that the Epson 2400 doesn't work (or doesn't work well) with non-Epson or thick papers. I have used many papers on the 2400 (from Ilford, Pictorico, Crane, Innova and Kodak), as well as Epson papers. Some are harder to handle than others, but none are "incompatible" in the sense of "can't be used without mechanical problems."
I have recently been printing almost exclusively on Crane Silver Rag, which is a very thick paper (300 GSM) and I have had NO problems with overspray, head strikes or pizza-wheel marking. Provided the paper is not curled to begin with, it's not at all difficult to print on. I've had paper-handling problems on the 2400 with some Innova papers, but it has absolutely NOT been my experience that you HAVE to use only Epson papers.
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Daniel Bell