Freezing here too while using Opera 11. This is on an older IBM laptop (1G RAM, P4), Win XP Home SP3 and the only way to fix it is to pull the plug (or battery, if I'm using it) and power up again and reboot, then it seems ok.
I have not tried to disable the rootkit scan.
I run the file, web, and network shields.
I never had this problem with version 5.0, but will wait for the temporary fix?
Otherwise, back to version 5.0
I updated through the GUI.