cubase: how to organize VST instruments and effects?

[Mario Berlinguer]

Hello fellow musicians
I am trying to organize the VST instruments and effects that I use with Cubase VST. I have them all in the Vstplugins directory. When I put some of them in a subdirectory ("strings" or "drums" or "guitareffects" etc.) some of them disappear from my list in Cubase, or some directories are not visible at all in the same list. Does anybody have a clue why this happens? Is there a limit of VST plugins that I can have?
Also... some of the plugins that came with Cubase are in a different directory. Is it safe to move them in the VST directory so that I can organize them too? (btw... why there are two directories for VST???)

thank you very much

Mario