On this Vista machine Dreamweaver 8 tends to disappear without warning and without error message. It seems to occur only when Firefox is open and it might be related to the use of the clipboard, but the problem also happens when the clipboard is empty.
Please save your files in DW on a very regular basis.
Sometimes DW8 behaves as if it were not compatible with Vista at all, and crashes after less then two minutes. Disabkling Aero has no positive effect.