Windows cannot access \\COMPUTERNAME. You do not have permission ...

Recently I have been setting up a workgroup network comprising three Win 7 PCs and one XP PC.

Two of the Win 7s can each access the other three PCs, but the third Win 7 says that I cannot access one of the other two Win 7s because I don't have permission. Previously I could so by entering my username and password. I have turned off this requirement on all PCs, but even if I try to restore it I no longer get the opportunity to enter username and password to access the other PC. So everything works on the network except this weird refusal.

The XP can access the other three PCs, except strangely I need to enter username and password when accessing one of the three. Annoying, but I will wear it.

The inability to access one Win 7 PC from one of the other two Win 7 PCs is obviously much more of a problem. I would be ecstatic if I had to enter username and password rather than getting a straightout refusal.

I have tried without success to find where Win 7 is getting the notion that I, the administrator, don't have the credentials to access one of my PCs. Can anyone help me stop this inane message popping up?

MilesAhead said:

Can you access the already shared Public folder on the said W7 PC?

If not, try turning off all firewalls, if you haven't already.

I am not sure how I would access a folder, public or otherwise, on the 'missing' PC since I initially access each external workgroup PC through Network where the names of the PCs are listed (or through icons on the Desktop). This is the case on each PC. The PC that causes the error message can see the three other PCs but can't be seen by the PC on which I am keying this.

I have used control userpasswords2 to remove the need for users to enter username and password on each of the Win 7 PCs, and Guest and myself are listed as users on each PC. Previously the Win 7 PCs could all access each other provided username and password were supplied. Strangely, the box containing the request for username and password would appear twice on the screen.

I believe that I have carried out the same procedure on each Win 7 PC, yet one attempt to open another PC fails. As I have said, in one case my old XP PC (merely the host of three printers and rarely used for anything serious) actually has to provide username and password to access one Win 7 PC but not when accessing the other two. I am unconcerned about this, but it is weird.

Sorry I can't see how to do what you suggest, but I have taken the opportunity to further explain the situation.

You can try to share a folder on the computer where you don`t have acces on. For example your D:\ drive.
You can then try to acces it from the other pc with \\Computername\D$.
That should put you on the D:\ drive of that pc.

You can if you want replace computername with IP address as mentioned above

MilesAhead said:

Can you ping the computer that won't allow access.
Open a command prompt and issue this command:
ping \\computername
or
ping ipaddress

I tried pinging the 'missing' Win 7 PC. It didn't work.

There is still one Win 7 PC that can't see another Win 7 PC, but the reverse is OK. That is, A can see B but B can't see A. But strangely since my first post the situation has reversed: now B can see A but A can't see B. Weird.

This means that the PC I am on at present can now see each of the other PCs without the need for username and password. So can one of the other Win 7 PCs. So can the lone XP PC.

This leaves the remaining Win 7 PC as the odd one out. Despite password access being turned off in User Accounts, when I attempt to access the 'missing' PC it is now asking for a password, which it then proceeds not to recognise! Just why it throws up a box (or sometimes two boxes!) and then fails to accept my administrator password may provide a clue to what is going on.

I should point out that the flawed but relatively benign situation I have just described can easily be upset by changing User Accounts. Ten minutes ago all hell broke loose around the network after I tried to reinstate passwords but somehow I have managed to get things back to just the one problem. One thing though. Password protection sharing is turned off in Network and Sharing Center so that my PVRs (Beyonwizes) can see my PCs. This may have some bearing, but hopefully not as I must be able to access media files stored on my PCs.

I am finding this issue onerous to explain and so I think it best that I get one of the networking gurus I know to come around and look at it on site. But if anyone has any further ideas I would be most grateful to receive them.

I have found a 'solution'. Trawling through scores of discussions on the unexpected inability to access a network PC from another network PC, I came across someone who had had success by not entering into the Enter Network Password popup box the administrator's name but 'User' instead. Not confident, I did the same and, bingo, the 'missing' PC was able to be accessed. Nonsensical but entirely welcome. Networking in Windows should be more logical. The error box should never have appeared, but seeing it had then surely the network administrator should have been recognised.