Pages '09 will refuse to open .doc/.docx documents that were created prior to 2000, or that have become damaged. That is an issue that can be resolved by installing the current, free LibreOffice Suite, opening the document, resaving it as .doc/.docx, and reopening in Pages '09.
Another potential issue is your upgrade to 10.13. The iWork '09 DVD installer writes dependent libraries and other files into operating system locations. An upgrade may have had an effect on some of these files (it should not, but still possible). I would reinstall from the iWork '09 DVD, and then follow that with the last update for iWork '09 with the iWork Update 9.3. That will give you autosave, versions, and better Word document compatibility. Pages '09 will be updated to v4.3.