It's hard to word this question, all of a sudden I'm experiencing this.. I'm able to drag my clips to different areas on the timeline, however I can't see the actual clip move until I unlick my mouse. There is the regular little box that shows me the amount of frames it's being moved, but I can't see the actual clip move, so where it lands is just a mystery..
Please tell us your system specs: OS version, Premiere version, amount of RAM, Hardware specs including graphics card and your source properties and sequence settings. Could be the driver for your graphics card needs updating. Have you done any OS or Premiere udpates recently or have you changed your system configuration?