Issues with activating the administrator account?

I activated my administrator account on my home premium for some strange (I
don't even recall) reason.
I used the local security policy. I disabled the account soon after, but
since then I'm having all kinds of weird problems like:

- The DRM components are not owned by SYSTEM, but an unknown user (leading
to all sorts of issues with mediaplayer - not able to play msn music store
songs)
- I'm unable to install a new display driver from nvidia - just stops at 50%
(169.25)
- I'm unable to install a new graphics card


It got me wondering if activating and later deactivating the administrator
account has side effects?
I read somewhere about the xxx-500 SID used by that account.
It may be that these are totally unrelated of course, but I wanted to ask
regardless. Thanks!