FSX install error 1935 Windows 7

Hello, im having a problem with a error in the installation of fsx on my pc, i bought the game almost 4 years ago, and i installed and everything worked fine (on Windows XP), then i upgraded my OS to Windows 7, and today i was installing the game when it gives a error right at the final of the installation when its "Publishing Product Information", i dont know what is happening... can somebody help me please? the error says: "Error1935.An error ocurred during the installation of assembly 'Microsoft.MSXML2,publicKeyToken="6bd6b9abf345378f",version="4.1.0.0",type="win32",processorArchitecture="x86"'. Please refer to Help and Support for more information."

My specs:

Intel Pentium 4 3.20Ghz
Ati Radeon x1650 (764mb)
2gb ram
Windows 7

last moment information, when it all "rolls back" in the installation, a final error windows shows up: "Error: -1603 Fatal error during installation.
Consult Windows Installer Help (Msi.chm) or MSDN for more information."

i forgot to say sorry: Thanks for all the attention