sounds to me like someone's got a taste of too much automatic, and maybe not enough manual file control. dw can be a savior, or your worst nightmare when it comes to project management. in my opinion, if you start in DW, and manage all of your files there from square one, and let it do all of the "update links" if you move a file location from one folder to another, and allow DW to always "synchronize the site", and all that crazy stuff, and chant three times while standing on one foot, the following: "i relinquish all file control to you, all mighty and expensive product" and finally stick a 10-pound note up your nose, then you shouldn't have anything to worry about.
my guess for those lost 4-days' work as mentioned above would be that the "Check In / Out" system blessed you with such goodness. i always disable the check in feature, that way i won't forget to "check in" any files which i have "checked out"-- a horrible, potentially maddening way of presenting the timeline of file versioning updates as such:
imagine 3 locations. home, work, and a remote server. Before retiring from work for the day, upload a file to the remote server at 17:00. now the remote server reflects that very file, last modified at 17:00. then later from home, open DW and look at your work. ask yourself 'which files are most current? which did i most recently modify, and which would show a state of progress as it was before any files were modified today at the workplace. you'll find that the files at home have the "oldest" date (perhaps even be 2 weeks older?) than those on the server, last updated from the workplace at 17:00. what if the files on the server are mistakenly disregarded for those at home? you have just lost your most up to date work because you wrote over any new material w/ the old files from home.
maybe that's what happened to those two weeks? in other words, and as thepeccavi is saying as well-- pay close attention to "Synchronization" and "Check in and Check Out" or, simply disable and don't use those features and/or use a separate FTP client.
