"Create random points" tool thinks I'm not licensed to use it

[SamR]

Hi all. I'm having trouble running the "Create Random Points" tool (in
the "Data Management" toolbox, "Feature Class" toolset) from
ArcCatalog. I get the "Tool not licensed" error message upon double-
clicking it.

The weird thing is that I seem to have all the right things registered
for this to work. The metadata for the tool says that it is "available
with an ArcView or ArcEditor license, if the Spatial Analyst extension
or the 3D Analyst extension is installed." I checked "Availability" in
Desktop Administrator, and it says that both of those extensions are
installed and registered, which is confirmed by my successfully
enabling them in ArcMap. It also says that I have a Single Use
registration; I cannot click the "Register Now..." button under
"Register Single Use and Extension".

Please help me get this tool working! If it helps, I'm running ArcMap
at my school on Windows XP. I do not have administrator privileges to
the computer. I am not at all familiar with the command line (in
either ArcGIS or Windows), but I'm not afraid to use it if you give me
step-by-step instructions.

Thanks in advance.