Copying files from HDC-SD300

Please excuse my bad English first.
Since about 12 years I use a HDC-SD300 above all for making films about my holidays.
For my last holidays I had 3 SD-Cards in use. When copying the clips on my computer I realized that some clips were copied not correctly. Only the first moment I can see a movement, than for the rest of the copied file I only can see a standing picture on my computer. On my camcorder I can see am movement on the whole clip. 
Before using the cards I only deleted the old files. I did not format them. 
Now I am looking for the reason:
Is it a problem of my camera, of the cards or of my computer. How can I find it out?
Sign In or Register to comment.