I have a 250 mb external hard drive. I use it to back up my files and photos. I noticed the files size doubles when i copy the files from my internal hard drive to my back up drive. Does anyone know how to correct this or have you encountered the same hard drive error?

What does the properties of the external hard drive indicate? is it the size of available space that's reduced or is the file size (folder) actually twice as big?
Is it your file size doubling? mac or PC?

Only thing i can think of is that yourcomputer might be making backup files on it's own, that's why it's doubling.

The files are 2x+ bigger. The file size double after copying. I use a mac. I asked a certified mac expert from sencolink, he said the there's problem with the directory. I need to reformat or they can help me for 3K, they can reduce 80% of the file size. I guess I'll just buy a new HD.

Are you using Iphoto? It makes multiple copies of images, large thumbnails and small thumbnails.

Nope, just making back ups of old files.