Conversation so far:
what was extended break?
during Silverchair's hiatus, the pair re-united and formed The Dissociatives.
What year was that?
2003.
What happen in 2004?
Silverchair performed to help raise funds for aid organisations working in disaster affected areas.
What was one of their side projects?
Johns and Mac released an internet-only EP, I Can't Believe It's Not Rock.

Question: What year was that?
Self-contained rewrite: What year was the release of I Can't Believe It's Not Rock?