A few days ago Dreamweaver CS3 stopped allowing me the ability to undo things whether I was in code view or design view. I thought maybe restarting DWCS3 would fix it, but to no avail. I did some googling and found a
post where people were saying you needed to delete the FileCache.dat file in the Macromedia application data folder for the user having the issue. This information did not hold so true for DW CS3, but it did lead me down the correct path.
My solution was to close DW and navigate to:
C:\Documents and Settings\<user>\Application Data\Adobe\Dreamweaver 9\ConfigurationIn there I found a file named:
WinFileCache-AD76BB20.dat Your WinfileCache file might be named slightly different, but it's the only .dat file in that directory. Rename that file or delete it (I always err on the side of caution) and restart Dreamweaver.