My computer at work melted recently (literally) and after IT rebuilt it I found all my FTP details for sites in Dreamweaver 8 would go missing every time I reopened it.
This is a bug with the IE 7 "release candidate", which does weird things to registry entries. Here's the Adobe technote:
http://www.adobe.com/cfusion/knowledgebase/index.cfm?id=3491671c
