I am going to assume that you are downloading parts of some images that have previously been deleted.
That means that the FIB (file information block) on the memory stick is corrupt.
You need to Format the memory stick with the Camera.
Since a Format will erase all the photo on the Memory Stick,
be sure and save to the computer - any photo files you want to keep.
Then use the Camera to Format the Memory Stick.
Look in the User Manual to see how to do a format with the camera.
A Format will write a new FIB on the Memory Stick.
When I download images from the camera to the PC there are horizontal stripes on half of the image from bottom up of images deleted a long time ago. Sometimes up to three stripes..Since I am taking pictures for someone else this is not acceptable..Please help.. Time is of the essence...Carolyn