On several occasions now I have experienced a lock-up with SP4. This has occurred a few times during legitimate online credit card payments, when SP4 suddenly warns that data is being redirected to different website than the one on screen. I cannot dismiss the dialog - none of the buttons function. The only way I can continue is to use Task Manager to kill the stpass.exe process.
I have Sticky Passoword 126.96.36.199 and Windows 7 x64, with IE8.