Observed with Windows 7 on 32-bit systems. No reports of this happening on 64-bit systems on Windows 7 to date.
There have been some reports that Microsoft KB update KB4088878 or KB4103718 could be causing BSODs or unbootable systems with Symantec Endpoint Encryption 8.2.1.
As a result of these updates, a system may either encounter a Blue Screen or encounter a hanging behavior when these updates have been applied.
Symantec Endpoint Encryption 8.2.1 has officially reached its end-of-life cycle (See article TECH143377 for more details). As this is the case, to resolve this issue, an upgrade to Symantec Endpoint Encryption 11 will be necessary.
If this is not immediately possible, please work with Microsoft to evaluate if a possible workaround may be available.