The User Data directory in the registry is not valid ... Error code: 0x851A0043

I've installed SQL Server 2014 on a new Windows 7 computer. I am trying to apply the SQLServer2014-KB3158271-x64.exe update which is the "3158271 Cumulative update package 14 (CU14) for SQL Server 2014." I am getting the error shown in the issue title: "The User Data directory in the registry is not valid ... Error code: 0x851A0043." I've check the registry setting for DefaultData and it has the correct path: E:\Program Files\Microsoft SQL Server\MSSQL12.MEMBERSLINK\MSSQL\DATA. The path exists, and has the database files. I've done this successfully before. The only difference this time is that E: is a network drive.

Help sorting this out would be greatly appreciated.