Sometimes SPS 2003 does not work properly with MS Office documents when you try to edit documents directly from SharePoint. Often times, a document will open as read-only even if you checked out the file. In the worst case, a document will crash, and you will lose all the changes. Integration between SPS 2003 and Visio files is especially unstable. The solution to any possible issues with editing documents is to download them to your local hard drive, and upload them once you edit them.

When you upload a document, make sure to check "Overwrite existing file(s)?" checkbox in SharePoint 2003 or WSS 2.0 (and "Add as a new version to existing files in MOSS 2007 or WSS 3.0). The uploaded document will not wipe out the version history. Instead, the updated document will be stored as a new version. Even if you upload multiple files, as long as file names match to those in a SharePoint site, all the files will be stored with new versions. Even though this approach is cumbersome than editing a document from SharePoint, you will not need to worry about losing all the changes you made.