if you access the "discovery tab" and right click (query) a lot of the addresses and select Query Now to enough of them it stops querying. For example it gets to the stage where you click query service and nothing will happen. When this happens the Discovery tab and the host chace tab can not be accessed by pressing F8 or F9.
You also have a problem when you go to close Shareaza when this happens. It Gets stuck on closing server processes. Have to ALT+CTRL+DEL and close the process Shareaza.exe.
To reproduce this bug open shareaza and query as many addresses as you can until it stops working properly.
This problem is on Windows Vista SP2 and Shareaza 2.4.0.0.