Startup disk full, but its not?

Empty the trash. Check available space. Still too large? Do this....

-- Open Disk Utility.

-- Select the "Macintosh HD" at left.

-- Select the "First Aid" tab.

-- Click the "Verify Disk" button (not the permissions button).

-- If problems found, they must be repaired by booting to another volume, such as the OS DVD.

-- Use Disk Utility when booted to the DVD to "Repair Disk".

-- When it finishes, click to repair again.

If no problems found at all....

-- Download OnyX.

-- Launch OnyX, enter password.

-- Select the "Cleaning" icon.

-- Select the "Logs" tab.

-- Check "Log files", "System Archived logs", "Instant message logs", and "CrashReporter logs".

-- Click the "Execute" button at lower right.

When that is done, check the available space. If no improvement....

Download and run "DS_Store Cleaner, free, link below.