Have been getting a problem with Mixcraft recently. Whenever I have more than 20 tracks my playback is reduced to a crackling, popping mess that is constantly change time... Everything mixes down fine and I can get some playback if I freeze most of the tracks. I'm not sure what the problem could be; the only thing that is consistent between all the songs I have made is the VST effect: VPS Philta and maybe some of the 'Classic Effects'. I use a lot of VSTi's in my projects however I usually always freeze them, mixdown them to audio, I always have any sort of eco mode on. My CPU is a quad core 2.3 Phenom and I have 6 gigs of RAM. My soundcard is the Presonus Direstudio Mobile and the drivers are up to date. I'm running Windows 7 Ultimate X64. Any help would be appreciated.