Last week one of my co-workers encountered a strange bug that in Dreamweaver 8 for OS X. It does not appear to be present in the Windows version. He was trying to edit an older page but the lower part of the page simply disappeared in Design View.
I searched the Adobe forums and found the following post about this bug though the postings are specific to large text files.
Problems with displaying large text files
In my co-workers case it wasn’t a problem with a plain-text file but instead an HTML file (granted HTML files are really just plain-text files, but I’m referring to the context of this file-type within Dreamweaver).
No solution exists but there is a simple work-around, which is to reduce the view zoom from 100% down to 66%. Though the text may be more difficult to view at least it can be seen.
This bug exists even with the 8.02 update. Hopefully, it’s been fixed in the CS3 release.