Folder Tree Has Disappeared When Trying To Copy To/Move To Another Folder

Hi,

I'm new to this sort of thing so I hope I do this right!

I'm running Windows XP Home Edition with SP3.

Recently, I noticed when I tried to move to/copy to from the Explorer window, my folder tree was blank in the little box that pops up. Regardless of whether I use the links to the left of the window or if I go into Edit - Copy To (or Move To), it happens with anything involving the explorer - documents, photos, etc. The only changes made recently was I had made an account on the computer for my kids, then deleted it not long after, without saving their folders (because they never used the account). Any other changes (installing programs, etc) happened after I noticed the blank box. It's not a major issue but it is slightly annoying.

Any ideas? And thank you ahead of time!