CANT PLAYBACK CERTAIN LOOPS

[em3]

I'm currently a 3.04 user and it works solid on my system. I've been checking out the newest 4.04 and downloaded the demo. I have spent hours with it and love impulse. But I am baffled as to why when I record in a track clip from my Triton studio in the sessions view as audio or even drag in certain looped clips, ableton only plays back half of my sample and will not loop it. Also, I select clips in session view and some playback continuosly while others stop after a one shot even though loop is selected. When in version 3.04 the exact same procedure gets me perfect results. I can drag samples in and they only playback unlimited some of the time. I really want the drum machine but at this point I really dont believe the version 4 works on my system. My sound card is the audigy on a top end vaio and I'm not running an ASIO driver just an mme driver. Also is there a way to add impulse and simpler to version 3.04 Thanks for any feed back.