Rendering an animation excludes certain frames (131-159)


I´m rendering an animation from frame 131 to 220 and noticed a problem at frame 159 so I interrupted the render process with escape.

Now when I try to start the render again from 131 it starts with frame 160 no matter what I do. I managed to start the render at frame 130 but then when it got to frame 131 it jumped to frame 160.

What on earth has happened to my Blender installation?

And of course I´m in a hurry to finish this animation project and was going to render the last frames while sleeping. Now it seems I will have to stay up and manually render frame by frame until I get to frame 160.

I´m using Blender 2.77 on a PC with Windows 7. And rendering with GPU.

Can someone plelase help?