it is hooked up by usb ?
what operating system is on the computer ?
have you tried a different usb port and cable ?
does it do the same thing from all programs or all documents or only very complicated documents?
That is probably a printer issue. Either the print head gets clogged and cant print after a page or sometimes the cartridges have a vent hole and if that gets clogged it cant get enough air in to replace the ink fast enough and it stalls then when it goes to print again by that time the vacuum is gone and it prints for half a page.
open the applications folder and look for epson printer utility
run that and select nozzle check
it should print out a nozzle check if that has gaps in it run the cleaning utility that it suggests next.
let me know what the nozzle check looks like please