"\\wombat2\d_drive is not accessible. You might not have permission to use this network resource."

First, disable Simple File Sharing in your windows XP

In Windows 7, open Local Security Policy with elevated administrator privilege. Under Local Policies, goto Security Options and look for "Network security: LAN Manager authentication level" and change the Security Setting to "Send LM & NTLM responses".

Description of this local policy is as follows:-

Network security: LAN Manager authentication level

This security setting determines which challenge/response authentication protocol is used for network logons. This choice affects the level of authentication protocol used by clients, the level of session security negotiated, and the level of authentication accepted by servers as follows:

Send LM & NTLM responses: Clients use LM and NTLM authentication and never use NTLMv2 session security; domain controllers accept LM, NTLM, and NTLMv2 authentication.

Send LM & NTLM - use NTLMv2 session security if negotiated: Clients use LM and NTLM authentication and use NTLMv2 session security if the server supports it; domain controllers accept LM, NTLM, and NTLMv2 authentication.

Send NTLM response only: Clients use NTLM authentication only and use NTLMv2 session security if the server supports it; domain controllers accept LM, NTLM, and NTLMv2 authentication.

Send NTLMv2 response only: Clients use NTLMv2 authentication only and use NTLMv2 session security if the server supports it; domain controllers accept LM, NTLM, and NTLMv2 authentication.

Send NTLMv2 response only\refuse LM: Clients use NTLMv2 authentication only and use NTLMv2 session security if the server supports it; domain controllers refuse LM (accept only NTLM and NTLMv2 authentication).

Send NTLMv2 response only\refuse LM & NTLM: Clients use NTLMv2 authentication only and use NTLMv2 session security if the server supports it; domain controllers refuse LM and NTLM (accept only NTLMv2 authentication).

Important

This setting can affect the ability of computers running Windows 2000 Server, Windows 2000 Professional, Windows XP Professional, and the Windows Server 2003 family to communicate with computers running Windows NT 4.0 and earlier over the network. For example, at the time of this writing, computers running Windows NT 4.0 SP4 and earlier did not support NTLMv2. Computers running Windows 95 and Windows 98 did not support NTLM.

Default:

Windows 2000 and windows XP: send LM & NTLM responses

Windows Server 2003: Send NTLM response only

Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2: Send NTLMv2 response only

If your system is Windows 7 Home Premium, you may change it from Registry.

1. Launch regedit from Start Search box.
2. Find the following branch.
 
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa

3. Create a DWORD key under Lsa and set:

Name: LmCompatibilityLevel
Value: 1

4. Restart."

Source: http://social.technet.microsoft.com/Forums/en/w7itpronetworking/thread/91fe4e10-a0d4-45db-94df-fad885d8f64f

Hi jackieman:

Simple File Sharing in my windows XP was already disabled.

I made the following change:

In Windows 7, open Local Security Policy with elevated administrator privilege. Under Local Policies, goto Security Options and look for "Network security: LAN Manager authentication level" and change the Security Setting to "Send LM & NTLM responses".

I still cannot open the shared drive from my Windows 7 PC.

Regards,
Leigh

Have you added files and printer sharing in the exception list of windows firewall of your xp?

Are your windows 7 joined to a domain? Or both xp and win 7 in the same workgroup?

Files and Printer sharing is included in the Exception list of Windows Firewall of my XP.

Both XP and Win 7 are in the same workgroup - for example, when I click on the Network icon on the Win 7 desktop it shows my XP PC - "wombat2".
When I click on "wombat2" it shows the shared volume "D_Drive".

What is the antivirus/ Internet security/ third party software installed in your xp and win 7?

XP has Avast! - I have disabled it.
Win7 has AVG Free 2010 and Windows Defender - disabled both of them.

I still cannot open the shared drive from my Windows 7 PC or another XP PC.

Remove Avast of xp and try again

http://www.avast.com/uninstall-utility

I have removed Avast off the XP PC using http://www.avast.com/uninstall-utility

I still cannot open the "shared" XP drive from any other PC .

Is the Firewall on Windows XP enabled? try disabling it too and check.

Also just make sure "File and Printer Sharing for Microsoft Networks" is added and enabled in Network card properties.

Sudeep

Have you restarted xp after removing avast?

Sudeep:

I tried disabling Windows Firewall on Windows XP.

"File and Printer Sharing for Microsoft Networks" is added and enabled in Network card properties.

jackieman:

I have restarted XP after removing Avast.

Remove AVG free 2010 in win 7.

http://www.bleepingcomputer.com/virus-removal/remove-avg-antivirus-2011

http://www.seasonsecurity.com/a/problem-with-avg-2011-free-edition-124240.html

Besides, make sure that your active network ia home or work network in network and sharing centre.

jackieman:

I am very reluctant to remove AVG free 2010 in win 7.
My second XP PC is reporting the same error, so I do not believe there is a problem at the Win 7 end.

jackieman:

On Win7 Work network is active in Network and Sharing Centre.

What is the antivirus installed in the second xp pc?

The antivirus installed in the second xp pc is Avast!

Remove Avast in 2nd xp pc and try again.

Hi jackieman,

I have a workaround that will let me access the XP files from the Win7 PC.
I can connect to the XP PC via Remote Desktop, then copy files from XP to a Win7 PC drive.
That is good enough for me.

I would like to close this question - I am happy to give you the points for your efforts - what do you think?

Regards,
Leigh