[EthoX]

found my 3year old on our computer, came back later to download a few items and that particular error window came up. i did reinstalled stuffit, but seemed not to help. any suggestions. or can i do a reinstall of those files or the system, of which it will replace what is missing. thanks for your input.

[Phoenix1701]

That error probably means that the file you downloaded was incomplete or corrupted. Your best bet is to re-download it. I'm not sure what this has to do with a three-year-old, though.....

[EthoX]

I did retry to download the original items again, and none of them will expand or mount. so I suspect it is something very serious, possibly.

[bradoesch]

You might try a little program called Mount.