Not able to access the Hyper-V host machine share from guest VM

To get rid off this problem disable NetDMA following these steps

1. Click Start, click Run, type regedit, and then click OK.
2. Locate the following registry subkey, and then click it:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
3. Double-click the EnableTCPA registry entry.
   Note If this registry entry does not exist, right-click Parameters, point to New, click DWORD Value, typeEnableTCPA, and then press ENTER.
4. To disable NetDMA, type 0 in the Value data box, and then click OK.

Source:

http://support.microsoft.com/kb/951037/en-us