Cannot open pdf
I've got some pdf files which can be open without any problem on Windows but require password when I try to open it on Ubuntu. As they are are not password-protected it is impossible to open them on my laptop. I wonder what is happening and if there is any way to open them in Ubuntu.
ASUS K53S Ubuntu 14.04 64-bit
ASUS U36jc, i5-480M, 2.66GHz, 4Gb, nVidia Optimus Ubuntu 14.04 64-bit
HP DV6-2113sa, AMD Turion™ II M620, 4Gb, ATI Radeon™ HD 4530 Ubuntu 14.04 64-bit
ASUS 1015PX Netbook Lubuntu 14.04