🚀 go-pugleaf

I previously asked about Apple IIGS with MacSE, got several helpful responses
and am now typing this with an SE with the aforementioned keyboard.  Thanks!

I had a problem a little while ago where I was unable to open Microsoft Word
documents by clicking on them.  The error message was something to the effect 
that the application could not be found.  I called up Microsoft (getting through
their computer touch-tone system) and the fellow told me to rebuild the desk-
top by rebooting with the command and option keys pressed down simultaneously.

Sure enough, after doing so, my Word applications open just fine.

Now I've had one Mac or another since 1984, but I never really got into the
esoteric side of it.  What exactly is rebuilding a desktop and what does it do?
Why did it fix my problem?  Are there any dangerous side effects? 
I like magic as well as the next guy, but years 
in computer science have taught me to depend on too much.

Thanks,

-rei