Network (home) ask for user and password

Greetings.
I have just clean installed my good old Windows 7 Ultimate x64 on my gamerPC. But that gives me a little problem I can't solve myself.
When looking at "my computer", "network" then I can see my WDLiveTV and my other PC (still running Windows 8.1). If I h´then want to open one of these to look in shared folders, then I am getting a window asking for username and password (name of the window is "Windows Security"), but both places has only a username and not a password.
I have disablet UAC completely in win7. I have tried this tutorial, Password Protected Sharing - Turn On or Off in Windows 7[2]=Networking%20Internet
"Password Protected Sharing - Turn On or Off in Windows 7" but with no success. Windows 7 is still asking for a username and a password. I also can't map a networkdrive for the same reason as above.

I'm quite sure it worked in windows 7 earlier, but I can't remember where to make the change. What has I forgotten?

This is NOT homegroup I'm asking about, but simple network sharing.

Well in the 8.1 computer ..in network sharing.. advance options..check out whether it has 64 bit or 124 bit encryption..that might be a hurdle (not sure)..just try it out

Both win 7 and win 8 use 128bit. Don't know what the WDLiveTV are using.

first find out whether your connection is public or work ..and then.. say if its work then relax the restrictions in work
profile..do this both on the computers ie..go to ..network and sharing..advance settings..chose enable network discovery..turn on file and printer sharing..turn on sharing so that any one with network access can read and write files in public folder...use 128 bit..turn off password protected sharing..

and make sure that its same for both computers ie both profiles should be the same

see if this works

P.S you can enable stricter restrictions later

That's excatly the way it is setup, and it does not work :-(
From windows 8 TO windows 7 it works fine, but from windows 7 TO windows 8 (or to WDLiveTV) it does NOT work.

Something is wrong in my windows 7 PC. When this was running windows 8.1, it has no troubble connecting to the other PC running Windows 8.1 or to the WDLiveTV, so it is clear, that the error is in my windows 7 PC, but I'm out of guesses, and I hope I will get the "golden touch" in here.

Oh, by the way. When I first tried to change the default setting to "password protected sharing" UAC did NOT promt me when I saved the setting!! (UAC was not turned off at this time). Maybe this can give you a hint of what is wrong with my setting?