A quick google came up with these results

http://www.microchip.com/forums/m357598.aspx
http://www.picbasic.co.uk/forum/showthread.php?t=1915

Seems that a lot of results point to the Epic programmer as being at fault in either not taking the PIC into programming mode, or not being able to erase the chip. Note that the programming voltage can be as much as 12v or more - whilst you think the epic is fine it might be worth checking that it takes the MCLR pin (check the datasheet to confirm) up to the VPP level at the time of programming.