Microsoft Visual C++ Runtime Library "buffer underrun detected" has only started to occur after installing v4. i realise plugins etc. might be out of date so i clean installed[no bookmarks, no preferences, install directory cleared etc.] same deal. firefox does not "Crash" in the traditonal sense (ie. "not responding" generic Microsoft window appears and u must select to close process... this... is different. i get the dialog box about the buffer overrun (and can quite happily continue to stream video/audio from the site i am on, until i click "ok" on the error and firefox craps itself... also at the point of crash and dialog box appearance i can no longer access new webpages- and the process stays in the list of active processes after clicking OK and must be killed before it can be relaunched... ) p.s. of the two types of crash i have experienced thus far, the buffer overrun is FAR more prevalent.