Strangely enough it only does this when working from external HD but when I select a clip and try to speed it up, or in fact use any of the efects, it renders instantly then just as instantly the clip returns to normal size as if nothing has happened, and nothing has.

I try again and the same thing happens, the clip is instantly 'shrunk' as it should appear when sped up (extended when slow mo) and instantly returned as if nothing has happened.

What gives?