Hi ABhinav,
If kernel is updated and not very old ,please check following
1. 117395 - Authorization problems for file I/O on Windows NT - Authorization of <SID>adm and SAPservice<adm>
2. 542000 - Messages "Error:18456".."Login failed for user 'xx'" appear
3. 1684408 - MSSCONCHECK: Cannot open database requested by the login - Check environment variables
Regards,
Archana