This problem bugged me for a while. I’m using one Windows 7 computer as an internal server. I prefer to access any member server in the domain using its local admin account. However, in this case, the local admin account can’t access any admin share on that machine, like C$. In the same time, the domain admin account can do that.
After checking around, I found that Microsoft probably blocked this feature in one of the previous updates. Generally speaking, that can be a really big security issue for any user and it’s a good practice to block those administrative shares, when you don’t need them.