Un-check 'Scan on startup' and then apply, close everything out, open sonar, plugin manager, THEN, see if you can manually scan.

just go to the plug ins you dont want and hit "EXCLUDE" in the plug in manger.
i do this with all my windows and direct x plug ins that i dont want showing in my personal created menu.

one should use the plug in manager to create their own menus.
at first it used to take me hours to design my lay outs.
now i have one for every thing i do
onr for synths,one for mastering,one for tracking,
learn about the manager man.
there is a good video on cake tv,sonar univercity videos

Its seems there is a problem with the naming convention of some files. Did you try to remove any "-" from you .vst file name?

Don't recall hyphens ever being an issue.