This can happen. OpenOffice.org does a great job of opening MS Office files, however it isn't a perfect clone.
I've found that most of my .doc files are fine, however there are one or two where the original settings haven't been converted exactly correct. Since I no longer use MS Office I've then edited them in OpenOffice.org and converted them to .odt (Microsof$ will soon realise they'll have to make Office compatible with this format when everyone starts moving over to it)
I only then make a .doc format copy when absolutely essential.