I'm having a bit of a nightmare.

I clicked twice on install by mistake when I was installing a plugin and all my installed plugins disappeared - I know that this is a known problem and you need to backup plugin.cfg - I had a reasonably recent copy so I uploaded that and most of the plugins reappeared. I was going through the process of moving the others from Installed to Uninstalled to reinstall them and my Uninstalled directory suddenly stopped responding. In ftp it says "Server returned empty listing for directory Uninstalled" and there is apparently nothing there. I can view all the files from shell but in admin the list of plugins is there and they all say "Unable to load plugin /path/Pluginname.tar Reason: Permission denied". It doesn't appear to be an ownership/permission problem. Any ideas what's going on?