How did Dobby know the Chamber was going to be opened?

[mrflynn6]

No: HPFGUIDX 42659

It just occured to me, how did Dobby know the Chamber was going to be 
opened and Harry was going to be in danger if he returned to 
Hogwarts?  Wormtail was still scabbers and not in touch with 
Voldermort yet, the DE's were not in contact with Voldermort, 
especially the Malfoy's.  Barty, Jr. was still under his fathers 
control.  How did Dobby know?

I should check my book for the exact quote, but Draco said to 
Harry/Ron as Crabbe and Goyle under polyjuice potion that his dad 
didn't know who opened the Chamber.  One would presume that Dobby 
knew from Malfoy's, but if they didn't know, how did he find out?

Any ideas?


Gretchen