No seek complete problems

first things first in my pc i have a nec 3520 burner and a nec 3500 i have had the pc for around 1 month from pc world and i have a prob burning dvds.

originaly it had a liteon dvdr in it but i kept getting a no seek complete error in nero so i thought it was the ide cable so i change it and was still getting the same error so i thought i would try different media so i tried tdx, traxdata, ritek, datasafe , datawrite and lots more but still had the same problem so i thought i would swap the burner to nec 3520.

now i have the 3520 i am getting the same problems i have tried burning at a slower speed and tried lots of media and even updated the firmware, but still not solved the problem i happens to around 50 % of dvds i burn if not more!

but if i use the 3520 to read the dvd and the 3500 to burn the dvds it seems to work fine ?

if you require anymore info please let me know