Why does windows (file) explorer try to connect to port 80 (http) instead just using smb?

Background:

On an almost freshly installed pc I get a message along the lines of : "windows cannot find some-file-server-name. Check the spelling and try again"... when trying to access any fileshare.

Troubleshooting so far:

• pinging works. Both by ip and by name
• the almost identical pc next to this one can access the file server
• everyone else can access the file server
• the pc in question can not access other open fileshares
• but it can connect to the internet

And now for what I think is the interesting part:

• running wireshark with ip.addr == local.ip.add.ress and ip.addr == server.ip.add.ress tells me that it tries to connect over http.
• the server replies but after a few messages back and forth it stops
• the other machine of course just uses smb

I guess port 80 just means it defaults to webdav, but I haven't been able to find anything that can cause this.

Googling it the closest thing I found was this http://www.techrepublic.com/article/get-vista-and-samba-to-work/6353849 but then again this was an XP pc and I wasn't able to connect to other native Windows shares (and I tried the solution anyway and it didn't work.)

If you believe it is WebDAV, have you tried disabling WebDAV client?

Services.msc -> webclient -> Stop/Disable

Also it's never a bad idea to use Process Monitor from SysInternals to see whats going on behind the scenes when something isnt performing as expected.

Turned out to be that "Client for Microsoft Networks" in "Local Area Connection Properties" had been uninstalled.

The way we discovered it was by making an educated guess into what settings could cause the problem and comparing settings from a working pc then looking into the differences we found.

After finding the cause the solution was to reinstall it: click the "Install..." button, chose Client in the list and follow the wizard.