This is one of those "funny" BSOD types which are a bit out of the ordinary.
The kernel itself is fine, but it has decided to call it quits (by BSODding) because it has noticed that a crucial user-mode process, in this case CSRSS (the Win32 subsystem) has terminated. In other words, CSRSS crashed first, and when the kernel noticed a short while later, it automatically did likewise because the rest of the OS cannot function without CSRSS.
There is no info in the minidump which would directly explain why CSRSS crashed. It's like a photo snapshot taken after the important event has already finished. While it's possible to directly troubleshoot the CSRSS crash, the methodology is complex and impractical over a web forum.
Hopefully your hunch regarding Norton being the cause is correct. Perhaps an update of the Symantec package will address the root cause(s) of the CSRSS crash.