If you are using Secure Deletion, emptying the Recycle Bin can take a very, very long time under certain circumstances. This problem can be caused by some minor data corruption in your Recycle Bin.
You have 2 choices here:
1 - Sit back and let it complete. This can take ages, but it will complete.
2 - Cancel the clean, deselect Secure Deletion and run the clean again.
Note you can tell that CCleaner hasn't crashed, as you can still move the UI and cancel the clean.