Windows 7: Cannot access a secured shared folder in xp pro, from win 7 pro

hi,
Computer A: windows Xp Pro
Computer B: windows 7 pro
secured shared folder in computer A with windows Xp Pro (documents$)
i'm able to access the secured shared folder in all machines that running windows xp, and server 2003, with the credentials that i've created( username, password)

But with computer B (win 7) i'm able to ping Computer B, but when i open the secured shared folder, it prompt to me to put the username and password, but when it doesn't accept , reprompt to put the username and password, and it doesn't open the shared folder....

I've try to re create another shared folder, i've put it public, that also, apart win 7, all win i'm able to open the shared folder

What i'm not understanding how any computers running win 7 , not able to open the shared folder on Computer B, but win Xp and Win server 2003 is able to open the shared folders???



thanks