Very Annoying Problem

Working in Dreamweaver CS3, go to put or save, I get an error message saying
that there is a file sharing problem, and the page does not save. I then hit
ctrl s again, the dialog box pops up and the file, which had been previosly
saved, is no longer in the pop up box.

Example...working on index, it has been saved previously, make changes, hit
cntrl s, or cntrl shift u, error message pops up, file sharing error, dialog
box pops up when I go to save again...index is gone, so I have to save it as
index again.

Any ideas... This was happening in DW 8 as well.

Gary