w00t, my first real problem with Windows 7. It wouldn't be Windows without one

Anyway, I am the sole administrator on my PC. I activate a guest account sometimes when someone else wants to make use of my PC.

All my music, videos, documents etc. are stored in the My Music, My Videos, My Documents etc. sections in my account folder. However, all of a sudden a few weeks ago when I tried to move some photos around my PC told me that I don't have the necessary permission to do that and as a result denied my access. I managed to play around a little and grant myself access to some, but now it's gone and messed up ALL my music folders. I can't manually fix them all.

I'm so confused as I didn't change anything, I am the only admin on the PC and it shows that my account has full control of all the folders in question.

Any ideas? So frustrating...