Unable to modify 2007 file on NAS server shared drive
 

I came accross with strange thing that I was not able to save the changes
done on my excel file stored at network.
When I try to save it give error access denied ask your administrator,
however the user has full control on that share folder. To cross check this I
test it with normal txt file, I am able to modify the text file.
The most surprising part is I can overwrite the file, I can create the file,
but when I try to one office 2003 file in newly installed windows XP(sp3)
system with office 2007 enterprise edition, I am poping up with error message.