vegas movie studio 12   windows 7  64 bit

all of a sudden, my frames won't snap to frames already  placed on track.

then too the playback in the preview window is off.  even after the frame has ended the preview is still showing the frame

I only started having these problems once I got the ad for an upgrade to movie studio 13/14.  I don't believe I changed anything before I started to have problems, but who knows.  I thought uninstalling and reinstalling movie studio would solve the problem.   but it hasn't. any help would be great thanks!