Hello, I'm hoping someone here may be able to help me. I installed Snow Leopard recently and I've got most things up and running without any trouble, although I am having an awful problem with skipping / stuttering during playback of HD movie files. I am experiencing this problem both in VLC and Quicktime. I did a little searching and the only suggestion I could really find was to select the "Use file memory mapping" option in VLC. I tried that but it didn't help much. I have a mid-2007 iMac with ATI Radeon HD 2600 graphics card. 2.8G C2D, 2G ram, running 10.6.1. The same 1080p mkv files played with no problems under 10.5.8. Any help would be appreciated. Thanks.