Hi! Hellion is right since I can reach it from XP and it can reach my PC when running XP. Thank you for your prompt answer but this problem only occurs when trying to access from Hellion to Windows 7 (not otherwise, pinging from Windows 7 to Hellion is Ok).
I already tried to tweak some policies as a result of googling as you said.
Just to leave a print for anyone interested, here's what I did:
- Start gpedit.msc
...then go to:
-> Console Root
--> Local Computer Policy
---> Computer Configuration
----> Windows Settings
-----> Security Settings
------> Local Policies
-------> Security Options
Microsoft network client: Send unencrypted password to third-party SMB server, and set to "Enabled".
Network security: LAN Manager authentication level, and set it to "Send LM & NTLM - use NTLMv2 session security if negotiated".
Minimum session security for NTLM SSP, and disable "Require 128-bit encryption".
Unfortunately none of that helped
I guess I must keep on googling.........