No defrag, Drag&Drop, Open in new window

I am running Win2k Pro sp3 on a network. I had problems with Symantec Antivirus & uninstalled the Live Update module, but must have screwed something up while troubleshooting (& messing with the registry).
1)Now I cannot run defrag,
2)drag & dropworks between L & R panes within a single instance of windows explorer, but not at all between two open instances, (although cut/copy & paste still work),
3)I cannot open a new iexplorer window with “open in new window” context menu option.
I believe this is a registry problem, but need pointing in the right direction, please!