while deleting history firefox crash with error of Script: chrome://browser/content/sanitize.js:136.So has to wait or cancel the script.

I have upgraded Firefox to 4.0.1.But while deleting history(everything) Firefox hangs for some time and then this error appears Script: chrome://browser/content/sanitize.js:136 is unable to continue.so either wait till process complete or stop the process.Sometimes it crashes Firefox.