Hello,
Symantec Endpoint Proteciton 12.1.2015 (RU2) supports Windows 8 client machines.
In your case, please collect Full Dump file and SST Logs.
Log a Case with Symantec Technical Support Team to get it reviewed.
Here are the Articles on how to create a Case with Technical Support Team online.
How to create a new case in MySupport
http://www.symantec.com/business/support/index?page=content&id=TECH58873
OR
Phone numbers to contact Tech Support:-
Regional Support Telephone Numbers:
- United States: https://support.broadcom.com (407-357-7600 from outside the United States)
- Australia: 1300 365510 (+61 2 8220 7111 from outside Australia)
- United Kingdom: +44 (0) 870 606 6000
Hope that helps!!