Windows 7: Windows 7 user intermitantly having READ ONLY to files at SBS 2003

I have a user just got a new Lenovo NB running Windows 7 Pro, previously was able to access from a NB running WIN/XPP to all designated files/folders located at a SBS2003 domain server with no issue. She does has full file/folder permission to the mapped network drive.
Now with her new Windows 7, she is experiencing 'intermitant' opening MS-office files, encountering 'File in use' message then the file would open as 'Read only'.
She would close it, then if try again, then she can open the file and edit/save.
This is happening to many of her files in different folders at the server.
I was able to monitor her actions via VPN remotely... when she can open a file fully I can see the work file with name beginning with '~' would appear in teh folder with attribute as HA. And whenever she encountering the READ Only message, I do not see the file name with '~' would appear.
This issue seems being reported in many forums however there is no real explanation for resolution. Last year I have 6 users encountered the same issue and finally reverted back to WIN/XP, then no such issue. This year I have 7 users upgraded to Windows 7 and rec'd no problem at all, but now one new user starts to see the old issue reocurring again.

HELP PLEASE!