Linking to my other post at https://www-secure.symantec.com/connect/forums/browser-intrusion-prevention-malfunctioning-0 but with a more accurate Title (for me anyway)
I'm now experiencing this at mulitple sites that have no relation to each other besides using SEPM. Internet Explorer completely locks up after which most other programs become unresponsive and you cannot shut the computer down.
I can trigger it by simply downloading CSV and TXT files from a few specific websites on Windows 7 w/ Internet Explorer 8 & SEP 12.1.5 although it happens in other versions of Internet Explorer too, most people have reported it from simple browsing to opening favorites they use every day.
If I run "iexplore -extoff" everything seems to be fine (not sure about other users and general browsing)
If I run iexplore as normal and disable the Symantec Vulnerability Protection BHO and Browser Intrusion / Network Threat Protection, it still crashes when downloading these TXT files (and randomly doing other things)
If I uninstall SEP12.1.5 everything works fine again.
I think this is a definition issue as SEP12.1.5 was installed 14 days ago and they do this process several times a day so it would have cropped up before now, only started this morning so it's must be something to do with 10/22/2014 r17, 10/23/2014 r2 or 10/23/2014 r17.
I'ev rolled back the definitions to early 10/22/2014 but have also told everyone that's reported problems to stay away from IE for the time being until i a confirmed fix.