Safari 5.1.7 reports all extensions invalid including AdBlock and ClickToFlash
I connect to internet at home(direct connect to internet) and office(throuth web proxy) on same macbook pro. Before update to Safari 5.1.7, AdBlock and ClickToFlash both worked fine in two place. After update to safari 5.1.7, safari always report that AdBlock and ClickToFlash is invalid when at office. But AdBlock and ClickToFlash work fine when I at home.
Anyone has some idea for this issue? Thanks.
MacBook Pro, Mac OS X (10.7.4)