Blue Cursor Problem

Hi all, 

For some reason my adobe premier pro blue cursor is jumping forward and back when I press play. Please see attached to see what i mean. Ive looked and tried to work it out but i cant seem to fix it. The filesi have are just standard JPEGS but even when i open up another project with a normal video its still the same. However, when I export it the videos come out fine but its rather annoying when i want to see my project.

Please can someone help? 

Thanks