After I had exhausted my cpability to think anymore and submitted my note, I remembered about the Fat & Fat32 formats that I had dealt with. When formatting with Fat or Fat32 the size on a single disk remained the same and visibly unchangable, although it was different from the size on the other disk. I read the help about the formats and expected some kind of resulting change equal to what you mentioned. I also noticed that on the messed up disk that approx. only half of the copied files are listed present with the addition of Norton's Recycled folder and the found.000 folder. Noorton isn't present on the other SD and still works fine on my PC. Is this disk possibly being treated as a permanent disk with need of changes in my bios? Not long ago I did have another hard drive in my system. Most if not all of those settings are on automatic, but you never know. I am working with a current Windows XP Pro OS. NTFS hasn't been a factor. After previously working with Win NT 4.0 I know that it is out of place here. I am trying to prepare an SD disk for my son's mp3 player to put this into context. I also use these same disks on my own Canon Powershot S2 IS Camera and as travel memory sticks with the readers as needed. Thank you Bob & Ramarc for your responses. I am hoping to be able to reformat, resize, or reconfigure the disk that is larger. I failed to mention that this last copy session I did placed the same amount of data (copies) to both so my hoping that setting a lesser max amount to put on the larger one as being a solution doesn't seem feasible. One last note this letter, I did buy the disk with a free reader as an incentive from someone on buy.com. I later found out it came from Hong Kong. I feel I shouldn't be alarmed by that but when investigating problems every detail matters and can be the final piece to the puzzle. Thanks again, This a first and I didn't expect this good of a return. Anything more with these added details I would love to hear from you. Tom.