Martin,
We could not replicate the issue with WAS 8.0.0.5. We see no issues starting the server in Debug mode.
Can you please share some other details with us?
1. How are you starting the server? Are you able to start the server without the debug?
2. Can you please try with a clean profile to rule out any issues with corrupted profile?
3. Is the profile you are using created as a service and has security enabled?
4. Can you please recheck if running MyEclipse as administrator (right click on MyEclipse Blue executable > Run as administrator) helps fix the issue?
5. Please let us know what exact errors you see when starting the server in Debug mode. Also share the complete stack trace to help us investigate further.
6. Please also share the .log file (rename it to .txt before attaching) which is located at <workspace dir>/.metadata/.log to help us investigate further.
Let us know how it works for you.