When you connect your Windows 7 system to network of systems like Windows Server 2003, Windows XP and Windows Vista, you may be able to see these network systems on the network but not able to connect and access resources even if you enter the appropriate username and passwords or have proper access rights (if in a domain). This may work OK from Non Windows 7 PCs.
This could happen if the LAN Manager Authentication level setup on the Windows 7 system is not compatible with the Non-Windows 7 PCs on the network. To resolve this problem, quickly check the LAN Manager Authentication level on one of the networked Non-Windows 7 pc and match the setting onto your Windows 7 PC.
To view/change LAN Manager Authentication level,
1. Click Start, search for “gpedit.msc” (Start – Run in Windows XP and earlier). This will launch the Local Group Policy Editor.
3. In the rightpane look for “Network Security: LAN Manager authentication level” and you should be able to see the set level. On a default install, it should be “not defined”. Change this to match or be compatible with the Non-Windows 7 PCs on the network. To change, double-click the entry and choose from one of the listed options. Click Apply and OK.
The defaults of are
Windows 2000/XP: send LM & NTLM responses
Windows Server 2003: Send NTLM response only
Windows Vista/Server 2008 (& 2008R2)/7: Send NTLMv2 response only
This should fix the problem.
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