diff --git a/app/models/submission.rb b/app/models/submission.rb
--- a/app/models/submission.rb
+++ b/app/models/submission.rb
@@ -113,7 +113,7 @@
     end
     if problem==nil
       errors.add_to_base("must specify problem")
-    elsif !problem.available
+    elsif (!problem.available) and (self.new_record?)
       errors.add_to_base("must specify valid problem")
     else
       self.problem = problem