The cache file is located on widows vista at:
In XP ist should be:
C:\Documents & Settings\[user_name]\Application Data\Adobe\Dreamweaver 9\Configuration
The file will actually be called something like WinFileCache-[some string of letters and numbers].dat
Stan, I'm glad your problem is soled. It was unlikely to be what I encountered. I had just installed Site Assist Pro 1.0.5 and UE 3.0.6 when my DW crashed and woud not open.
It turns out that I happened to run into the rare css file size error that existed in DW8 and apparently still exists in CS3. I had onl;y encountered it once before.
Of course I did not recognize it and wasted time installing and uninstalling extensions and restoring backups.
For anyone else who's problem is not resolved by deleting the cache file, check to see if you have a css file that is about 8kb. If any of them are, open them in a text editor and add a comment like
/* This changes the file size */
When you have done that to all the css files that are about 8kb, try to open DW again.
DW crashes if an external css file is exactly 8192 bytes (or a multiple thereof).