Could not read metadata for 'C:\Users\Darrin Kay\Application Data\Adobe\Flash Catalyst CS5.5\workspace\.metadata\.plugins\org.eclipse.core.resources\.root\.indexes\properties.i ndex'.
Unexpected version: 0.
Hey man, I got the same problem, I noticed som message saying "flushing ..." So I looked up for the file mantioned in the directory displayed in the error message... You may need to make visible your hidden folders.
When you get to the folder, you'll have three files, just delete properties.index (perhaps you may like to create a backup) and start once again Catalyst.
That worked for me... Hope it does the same for you.