and another!....playback stops when looping in sonar

[r0cker]

hi, i'm being a bit greedy today, i have two problems! anyway my problem is that when i set a loop to playback in sonar playback will stop after the loop has played the second time round. so it will play the section thru, go back to the start play it again and then stop just before the end of the looped section. my disk and cpu settings aren't high so i dont think it is lack of processing power and it always seems to hapen at the same point wherever i am in the track (ie at the end of the second playback of loop)
my system config is:

800mhz athlon
256 mb ram
turtle beach pinnacle

any help would be well appreciated as this is slowing me down quite a lot!
thanks in advance
r0cker