Can not open PDF files from Read-Only (undeletable) USB Partition

[ee25930506906l]

I keep getting error message whenever I want to open PDF file from a Read-Only (undeletable) partition of a USB Flash Drive.

However, I can open the PDF when its copied normally to the USB Drive or CD partition.

Somehow the PDF reader can not open the PDF files when its made in a read only partition. 

Does it make sense?

I hope you know how to fix this?

[Test Screen Name]

What error message?

[ee25930506906l]

this is the error message: "Adobe Acrobat Reader could not open ......PDF because it is either not a supported file type or because the file has been damaged (for example, ,it was sent as an email attachment and wasnt correctly decoded).

But when I copy the file and paste into my computer, then it can be opened without any problems.  Somehow the Read-Only Partition Drive cause this error message. I think it must be something about the encryption. 

[radzmar]

This is very likely the reason.