I don’t think this is a Toad bug. I think the problem has something to do with your environment.
Read this, the solution may be to change a SQL Net parameter.
From: salmon5 [mailto:firstname.lastname@example.org]
Sent: Thursday, May 16, 2013 5:59 AM
Subject: [Toad for Oracle - Beta Discussion Forum] toad reconnect bug
when toad reconnect to a session,is prompt ORA-03135,the bug appears.it’s exist in toad 11.6.1,toad 126.96.36.199-188.8.131.52.
the attachment file is a video appears the problem.(1,the bottom windows appear a blank area.2,cannot exit toad unitl kill toad.exe in taskmgr.)
my os is xp sp3 32bit,toad 184.108.40.206.
waiting for you reply,thanks.