The preamble can be found here:
https://community.norton.com/en/forums/latest-update-causes-ie-and-firefox-bomb-out-initial-open
Two questions directed to Norton-Symantec:
1. Is NAV version 21.7.x.x compatible with older computers having SSE CPUs (not SSE2)? According to this link, the answer is yes:
https://support.norton.com/sp/en/us/home/current/solutions/v101962385_EndUserProfile_en_us
2. If compatible, can you investigate/confirm if a recent update of IPS/IPE (or any other module) may have included (by oversight) code requiring SSE2.
From my own Security History I note the following update sequence:
05/05/2016 17:54:20,Info,Intrusion Prevention is monitoring network traffic for signatures. Driver version: 15.1.0.1263,Detected,No Action Required,Intrusion Prevention,No Action Required,No Action Required
05/05/2016 17:54:20,Info,Intrusion Prevention Engine version: 7.6.0.217 Definitions Set version: 20160504.001,Detected,No Action Required,Intrusion Prevention,No Action Required,No Action Required
05/05/2016 17:31:52,Info,Intrusion Prevention is monitoring network traffic for signatures. Driver version: 15.0.2.19,Detected,No Action Required,Intrusion Prevention,No Action Required,No Action Required
05/05/2016 17:31:52,Info,Intrusion Prevention Engine version: 7.4.0.83 Definitions Set version: 20160426.001,Detected,No Action Required,Intrusion Prevention,No Action Required,No Action Required
After the update to Driver version 15.1.0.1263 and Intrusion Prevention Engine version 7.6.0.217 both IE8 and Firefox 45.1.1 won't run. As explained in detail in the preamble.
Workaround: in my case, I re-imaged the c: drive to before the update and then I switched off all automatic updates. Definition downloads are done manually.
Thanks in advance.