Changing sql server service and sql server agent service startup account in SQL Server hosting SharePoint DB

i have a sharepoint deployment with one SQL Server (running on VM) hosting the config DB and another SQL Server (Physical Host because VM was running out of space) to host the huge Content DBs. I need to schedule automatic backups of the Content DBs to a network share. For that i need to run the SQL Server Service with an account having permissions to the share as suggested in http://ift.tt/1HJZ9Mc

I tried changing the logon as a service account to a domain account which has permissions to the Network Share and is also in local Administrators group of SQL Server and has "public and sysadmin" roles in SQL Server but that caused an issue. the SharePoint Web Application started showing a White Screen so I had to revert back to the default accounts i.e. NT Service\SQLSERVERAGENT and NT Service\MSSQLSERVER. I viewed the event logs . These are the types of error i got after changing the logon as a service account to a domain account

1) Information Rights Management (IRM): Retried too many times to initialize IRM client. Cannot retry more. Retried times is:0x5.

• System


• Provider [ Name] Microsoft-SharePoint Products-SharePoint Foundation [ Guid] {6FB7E0CD-52E7-47DD-997A-241563931FC2} EventID 5148 Version 15 Level 2 Task 9 Opcode 0 Keywords 0x4000000000000000


• TimeCreated [ SystemTime] 2015-02-02T04:46:04.750899500Z EventRecordID 176477


• Correlation [ ActivityID] {8FACE59C-1E17-50D0-7135-25FDB824CDBE}


• 
  

  Execution [ ProcessID] 6912 [ ThreadID] 8872 Channel Application Computer

  
  


• 
  

  Security [ UserID] S-1-5-21-876248814-3204482948-604612597-111753

  
  


• EventData hex0 0x5

2) Unknown SQL Exception 0 occurred. Additional error information from SQL Server is included below.

The target principal name is incorrect. Cannot generate SSPI context.

• System


• Provider [ Name] Microsoft-SharePoint Products-SharePoint Foundation [ Guid] {6FB7E0CD-52E7-47DD-997A-241563931FC2} EventID 5586 Version 15 Level 2 Task 3 Opcode 0 Keywords 0x4000000000000000


• TimeCreated [ SystemTime] 2015-02-02T07:01:35.843757700Z EventRecordID 176490


• Correlation [ ActivityID] {50B4E59C-5E3A-50D0-7135-22AD91909F02}


• Execution [ ProcessID] 6912 [ ThreadID] 5452 Channel Application Computer


• Security [ UserID] S-1-5-17


• EventData int0 0 string1 The target principal name is incorrect. Cannot generate SSPI context.