HUH? I haven't had any problems opening files with MS Office. I've had problems opening MS Office-created files with Open Office. And why on Earth would Microsoft be responsible for whether or not open source software can open Microsoft-created files? That's sheer silliness. Microsoft is in business to make money, not to support the open source movement. And it's Microsoft Word's .doc format that's the world standard for documents; it's Open Office's responsibility to handle those files if it's to be declared "fully compatible with Microsoft Office files."
BTW, I have nothing whatever against Open Office or open source software or Linux. In fact, I've said Open Office is an excellent choice for someone on a tight budget who needs a productivity package.
MM
The problem is that with being the world standard comes a responsibility to allow others to be able to read your files. Unfortunately, Microsoft keeps the format closed, preventing perfect compatibility. I'm sure they also have portions patented so they can sue if they feel like killing some competition.
My budget's not tight. I simply prefer OpenOffice.