Ant <input/> no longer working in Eclipse Helios (3.6)-Collection of common programming errors

I have a build file in my Eclipse projects. One of the things this file does is ask a question via a prompt, using the tag. Since upgrading to Eclipse Helios, this no longer works, as I’m getting the following error:

[input] ***WARNING: Display must be created on main thread due to Cocoa restrictions.

Invalid thread access

How can I fix this error?