Pure Musics Memory Play


I recently installed a trial version of Pure Music. I'm using a Mac Mini i5 2.3 Ghz- and up until yesterday had no issues. I upgraded my RAM from 2GB to 8GB and now I can no longer use the Memory Play function. When I select a track it says 'Loading Tracks Into Memory' and Pure Music freezes...I'm assuming my RAM is fine as my machine is working with video content and normal playback. I'm using iTunes version 11...any suggestions?

If the Memory Play tab is de-selected in the Music Server banner I get playback...

Any feedback would be appreciated, I've only had the software for two days but now I'm questioning making a final purchase.