What is the standalone player?
How old is it?
Is it a brand name player? or is it a cheap and nasty from the discount store?
Some players also prefer DVD+R that hasn't been bitset.
My brother bought himself a DVD player because it was that cheap, it was worth it just for testing. Damn thing wouldn't play ANY burnt DVD's and had lots of trouble reading pressed DVD's for that matter.
Luckily he already had a much better DVD/Divx player.