Go into your admin panel to Tools>System Information.
Select the permissions tab and make sure the folders are all "Writeable".

Thanks Breck.
Yes all folders writeable. I have maybe 6 products that won't allow me to attach images. The (100) others seam fine.

Thanks Rune.
Have looked further for a solution, seams to be some kind of path issue with the product listing. Doesn't mater which image I load for those product listings same thing happens, even images that will load on other products won't upload. (Next step I guess is delete product and start again, just thought if its an avoidable issue or mistake i've made I and others could learn from a solution)
Have googled for similar issues and found the following related problems ( Sorry don't know much about code, but think it maybe related ).
The code below is from my site.
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A solution I found to a similar issue in a Prestashop forum. Could it be related?
Looks like the Vantage theme you have was generating the header through a PHP script. Something in that script was triggering an error with PageSpeed that wouldn’t let it parse the data properly. I’ve made some tweaks and it seems to be working fine now.
Thanks James

Just to add to above. I turned Google pagespeed off and cleared the cache, didn't seem to make a difference.

If you upload the images through FTP to the folder, can you select it when editing the product and will it save?

Can upload images through FTP (cheeked original file perms were 644 ). When I try to access the image folder through products edit image , the file is blank as in first post. However I can now load images from some other folders (maybe since yesterday it was a cache issue). Not shore if there was some issue with folders the images were in so deleted them also and created new image folder.

So as Rune suggested, Looked at original images that would not load and cannot see any difference data wise, but must be an image issue, because I can now load other images.

Thanks for all suggestions.