Adobe Acrobat 7.0 document error

Hi,
I am using Ubuntu 7.04 along with plugin for Firefox and have successfully installed Adobe Acrobat 7.0. Adobe Reader is able to open all PDF file but it requires ID Password for PDF created by Service Centre.
Adobe Reader opens the Document so created in Windows XP (requires Internet Connection) but it generates an error message in UBUNTU 7.04 and fails to detect the Internet connection, though Firefox happily broses even the adobe site. I tried every step that I can but I can’t do anything without expert’s suggestion so help me to resolve this error. Thanks.

Error Message: This computer must be connected to the network in order to open this document.
Your ability to open this document offline has expired. If this computer is not connected to the network, please connect this computer to the network and then try opening the document again.
