\computername doesn't work (while \ip do)

Got a problem which I've searched for and many seem to have the same problem
but have yet to see an answer to it.

typing \\ip (i.e. 192.168.100.xxx) works great, every time. But typing the
computername instead, like \\media does not.

I got it working by disabling the firewall before and found out that the
"Registreringstjänst för Datornamn för Windows Collaboration" (thats swedish
- my attempt to translate it would be "Registrationsservice for computernames
for Windows Collaboration" (not a big fan of localized software)) exception
in the firewall resolved it.

Problem is I restored my computer using System Restore due to a faulty
driver and since then I haven't been able to get access to this again. Even
with the firewall completely off.
I have enabled file-sharing in the network properties and the \\ip do work
(and always had).

Don't know if something got messed up in the system restore but as said,
this is a common problem so there should atleast be some solution to it.