Windows 7: Troubleshoot sharing

I used to have the following setup with 2 XP boxes, following the guideline at
Windows XP Professional File Sharing


Group: Home
Box A has account x and y
Box B has account y, password of y is the same as on A
Box A shares folder mp3, permits y to read it
Box B then opens \\A\mp3, without a password
This has worked for years, until I upgraded A to Windows 7 64 bit.


First, B loss access to A if A resumes from hibernation.


Someone suggests that I should use "Work Network" in stead of "Home Network" since I am mixing Windows 7 and XP.
Networking home computers running different versions of Windows


I followed the suggestion and things got a lot worse: B can no longer access any shared folder from A. B will get a logon prompt in stead. When the same account x and password is entered, logon will fail -- the prompt appears again immediately.


I switched it back to home group. Same.
Switched group, reboot; switch it back, reboot. Same.
On A, event viewer shows log on and log off from B. Nothing unusual.


How can I troubleshoot this one?




Thanks!