mouse pointer too fast

When I grab a vertex I have noticed it moves too fast all of a sudden, and this happens with only this .blend file. I have just tested on a new .blend file and the mouse movement is very smooth and of normal speed. Has anyone encountered this problem before. This is the second time(in about two months) that I have experienced this.

I am currently using Blender 2.58, and had a previous similar experience in Blender 2.57, but only with this .blend file.

Any help would be greatly appreciated.

I don’t see your blend file. Have you got snappining enabled (the magnet icon on the 3dview header)

Thanks a lot, I disabled and enabled the snapping button (magnetic icon) and it works again.
I hope it doesn’t happen again.