Networking - Access is denied but it shouldn't be

I have this strange problem. My computers/laptops are networked correctly (in my opinion, they're able to share files with each other normally etc.) but certain files are not allowed access even though they're in the shared folder. These files are not encrypted.

Isolating the problem further, it seems to only happen when I download these files onto the laptop first. As in the permissions/access to a file from the desktop to laptop is fine if it is downloaded onto my desktop. However, if the file was downloaded onto my laptop first and if I tried accessing it on my desktop then the permissions are denied when trying to access it.

Does anybody have any idea of what is going on? The only fix I know of at the moment is to resave these files on the laptop once they're downloaded. But it is a serious waste of time doing this over and over again, anyone know what is going on?

 

What permissions do you have for the folders that are being shared?

 

When you say resaving it fixes it, do you mean you make a copy of the file on the desktop and then that one works from the same location? If that's the case, the only thing I could think of would be that an attribute is getting set on your files when you download them. Are you using a standard browser like FireFox or Internet Explorer or something different? Have you tried downloading the files in a different browser to see if the problem persists? It could be a permissions problem caused by the file being in use on the laptop. I personally use a free piece of software called Unlocker for a similar problem I sometimes run in to, you might give it a try to see if the files are locked because of a permissions handle that Explorer isn't releasing.

Can you copy any other non-downloaded file off the desktop okay? If you reboot the computer and try to copy the non-copyable file again does it work after that or does it still deny you?

 

I already use Unlocker =/ The file is not in use as far as I know. I use Firefox.

By resaving, I mean if I copied and pasted the file in the same directory, then deleted the original copy, the new file actually transfers even though it is a copy of the original file... I hope that made sense.

The permissions are 'Share this folder on the network + allow network users to change my files'