Cannot disconnect network drives in Windows 7

Some Googling reveals someone else that had this issue. The problem was down to an issue with a registry key. Their issue was on Windows Server 2008, but the same principle for Windows 7.

Open Regedit, and navigate to the following key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\NetworkProvider\Order

Find the string called "ProviderOrder", the value should be a string with multiple values separated by commas (for example mine is: "RDPNP,LanmanWorkstation,webclient,BCMLogon"), ensure "LanmanWorkstation" is one of the values.

Credit / source: http://panerarichang.blogspot.co.uk/2011/07/win2k8error-code-0x80070002-system.html

Update: I was able to recreate the issue you faced by removing "LanmanWorkstation".

I had the same problem but it was caused by a defective NFS4.1 driver installed by a Windows NFS client I had had used recently.

Inspired by other answers to this issue, I checked this Windows Registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\NetworkProvider\Order

I had a string value named ProviderOrder containing this data: nfs41_driver,XwpNTrdr,RDPNP,LanmanWorkstation,webclient.

Unlike other users reported, LanmanWorkstation did appear; the problem was caused by nfs41_driver. Just remove it off the list and it will work again.