Sounds really much like a permission issue.
Perhaps the Windows user you are using need to be part of Windows group for ASE_DBA (I don't know ASE on Windows but I am thinking about the Oracle Windows group such ora_dba).
1) Could you check if there is a Windows group for ASE?
2) Is your Windows user the one used to install ASE? If no, could you login with that user and see if you can open the log file?