lyx win32 strange margins preview issue

[Felipe Leon]

Hello, Im new to the list and to lyx and to latex all together. Please 
be patiente if my questions are obvious :-)
I installed previously the version of lyx (1.3.1 I think) which needed 
all the stuff like cygwin and the X server. It was working ok but I 
decided to install the native win32 version of lyx. Everything went 
smooth, I had all the pre-requisites: miktex, ghostscript, the fonts, 
etc. I configured my working path, the pdf viewer, etc.
The problem arises when I want to see the preview of a document either 
as a pdf with acrobat reader or as dvi with "yap". The output looks a 
bit strange because the margins are not the same for the entire 
document. There is a pattern and this is that the even pages have the 
text shifted to the right. So for example in the odd pages the left 
margin is 4 cm and the right margin is 4.5 cm but in the even pages 
these margins are 6 cm and 3 cm respectively.
Does anybody has any experience with something like this?

Thanks a lot in advance.
by the way, I didn't uninstall the non native lyx , but I cannot 
remember if the situation was different when I had only that version 
installed in my computer.

Felipe.