I have a 1TB and 2TB Western Digital My Book USB drives along with WDTV box for playing the media on a TV. I also use Windows 7 and I have never faced any problems you have just described.
These drives require SES
drivers for correct functioning. Do you have SES
driver installed on your Window 7? (check in Device Manager). If not you will find these
drivers on the WD Smartware software.
I am enclosing my drives permissions and ownership details. You may compare these permissons with your HDDs and if necessary correct them.
WDTV does not change the NTFS file permissions on the HDD. It only creates a database index of media you have on the HDD. You will find the database entries in .wd_tv folder.