I am experiencing this issue, but I do not have an entry for Windows Live ID Sign-In Assistant in Add/Remove programs on Windows 7. But I do have Windows Live Sync Beta installed.
My take is that since I can still browse my file shares from other computers (even through Hamachi), this is an issue with the way the WDTV Live manages authentication.
I will report back after removing Live Sync Beta.
UPDATE: Removing Live Sync Beta did not correct the issue. I had WIndows Movie Maker installed as part of the Live Essentials package for quite a while and the WDTV worked fine. Next step is to remove the whole **bleep** package.
