Here is something to look at for a possible future bug fix.
As a fairly new ToadOra user I managed to lock Toad for Oracle 11.5.1.2 up tight after shutting off the option to display ROWNUM in the database grid.
Just before changing the setting I was browsing table data on an Oracle 11.2.0.1.0 database using the full 11.2.0.1.0 client.
I’m running on a Dell OptiPlex 990 w/ 4GB RAM, WinXP SP3 32, on the primary display of a dual monitor setup.