Any solvents that would dissolve the paint will also damage the finish on the poly. If this was recent and it was a latex paint, you may be able to scrub the paint off with 409 and a kitchen scrub pad.

If you can't scrub it off, your best bet is to scrape it off. I'd try first with a plastic putty knife. If that doesn't work, try a single edge razor blade. It will be easiest if you buy one in a holder. You can get either tool at Walmart in the paint department.