Windows 8 PC cannot access files on Mac OS 10.9.4

I have a mac and a PC running on my home network. The iMac runs Mac OS 10.9.4. It has a netbios name of IMAC, and the computer name is imac'. In system preferences I have turned on filesharing, shared a folder calledmusic, turned on SMB and AFP, and set the workgroup name toSWAMP. My PC is running Windows 8.1, and I have set the workgroup toSWAMP` on this machine.

I would like to access my shared folder on the iMac from the Windows 8.1 machine, but I cannot. The iMac doesn't appear under “Network” in file explorer, and I cannot map a network drive; I get a dialog box with the error:

Windows cannot access \\IMAC\imac\music

The error code given is 0x80070035. The iMac is connected to my router via an etthernet cable, so it always has the address 192.168.0.2, and I can ping this address from the Windows 8.1 PC successfully.

I have Windows firewall and the Mac firewall on, but I don’t see any problems with the settings. File sharing is enabled on both machines. Netbios over TCP/IP is enabled on my Windows PC. I have restarted both machines and the router a hundred times. There is no homegroup on my network. Both machines connect to my home network, my printer and the internet fine.

I am also unable to connect to shared folders on the windows PC from my iMac using either CIFS or SMB.

The Server is unavailable at this time.

How can I see my shared folder on the iMac from the windows 8 PC, please?

Edit: I borrowed a windows 7 PC, and I could access the share folder on the iMac at \\IMAC\imac from that windows 7 machine exactly as one would expect to be able to. So there appears to be something about how windows 8.1 and mavericks communicate.