I am using DW CS4 on Vista and My file cache is as follows...
Users\(username)\AppData\Roaming\Adobe\Dreamweaver CS4\en_US\Configuration\WinFileCache*****.dat, (where asterisks represent numbers).
I am pretty sure from your path name that you are running CS3 under XP
if you are unsure whether it is the right file to delete, simply rename it or change the extension instead if deleting it.
Dreamweaver will recreate the cache file next time it starts.