Windows 7: Map network drive fails to retain password after reboot

Hey guys and girls (where applies),

I have Win 7 ver 6.1 (build 7600) on Desktop and I have a Linux server. I don't use a password to logon to windows.
I successfully mapped Linux drives using my Linux user (which happens to be the same as the windows user) but on Linux I have a password. All the mappings were OK (4 directories) asking me on each one username + password + ticking the box called "retain credentials".
All went OK until I rebooted, then a message pop-up that "could not reconnect all network drives"...appeared: => the old stupid message from win XP.
Ok I opened My computer and surprise: My user and my password from the sharing pop-up window were gone! I've inserted them again and all went OK.
I thought they solved the old windows XP problem which clears the user + password from the Network drive mapping IF you do not have the SAME password as the mapped drives.
What can I do to retain that User+Password combination for good in Win 7 Mapping?

Thanks in advance.
Chief