I was having that problem after applying a second coat of some enamel spray paint. The problem was, I was not allowing enough curing time for the first coat, and the second coat was lifting the first coat. The humidity was a bit high, which probably lengthened the required curing time. This was on bare, clean metal.

Read the can carefully, and perhaps try a different brand of paint. Some say to recoat within a couple of minutes or after 48 hours, some say recoat any time within the first hour, and some say to wait one day instead of two days.