Acrobat reader defaulting to 51% zoom size when opening and printing Report

Question

We are publishing reports on a web-integrated acrobat reader. All the reports work fine except for 1 report. The problem with this particular report is that when it opens up in the acrobat reader, it's zoom size automatically defaults to 51%. Then when we print it in landscape mode, it prints with the same zoom-size settings. Even if we try printing after expanding the zoom size to 100%, it still prints to the smaller size and leaves nearly 40% of the paper blank. It works ok with client-server settings as well as when we use HTML or HTMLCSS format to print on the browser. We are using the run_report_object built-in to open the report which is a parameter report.
Other reports with identical settings work and print fine. Is this a Oracle Reports problem or acrobat problem.
We are using Forms 6.0.8.19.2, Reports v6.0.8.18.0, iAS v1.0.2.2.2a, Acrobat reader v5.0, IE 5.5 with SP2, Windows 2000 Server.
Report fonts are Courier New with size 6.
Any ideas/solutions aprreciated. Thanks!

Answer 1

And so.. what is invalid?
I've uploaded the pdf files as example:
My generated pdf
http://compuhelp.free.fr/adobe/before.pdf
The modified version by Adobe Acrobat Reader:
http://compuhelp.free.fr/adobe/after.pdf
(I can generate a more complexe pdf file with fonts, images,... it will be displayed correctly, but Adobe always want to modifiy it).
So perhaps I missed somthing into the pdf file format specification ?