Vista - VHP to Windows 2003 server

Interesting problem and hope that someone can help.
Am running a small <15 user network using Win 2k3 server with a domain.
All clients are XP Pro and using sharing can access requisite folders and files with no problem and can block domain users via sharing from accessing secure folders.
I have 1 Vista Home Premium laptop that can access the domain shares with no problem except for the fact that there is one folder with 3 xls files that the Vista user can see and can write a file to that folder as they have Full access to that folder. However, they can access one of the xls files just fine and can change it and so forth. The other two xls files they receive "Access denied". All 3 xls files are of the same type and created with no difference as they are of different locations within the organization. Same xls file just different data. The Vista user logs onto his laptop using the same username and password as his domain account.

Interesting sidelight as when he logs onto an XP Pro workstation using his credentials (log onto the domain) he receives the same error for the 2 xls files.
I have deleted and recreated his domain account and also recreated the share and security permissions on the folder in question. No one else has any issues with this.

Does anyone have any thoughts as to the cause?
The folder in question is a child folder of a parent folder that gives everyone Full access but does not inherit permissions.
TIA
Saavik