I can move any of them out and they disappear.  I can move them back and they reappear in the Tool Administration list.  I just tried with several.

BTW, I'm using CentOS.  I transfer the plugin zip file to the server and use "unzip tidypics.zip" to extract the files/folders.  Could "unzip" be doing something to the files?  Everything looks fine after the extraction and I can open/view the files.  I'll try unziping on my PC and SFTPing them to the server...

... nope that didn't make a difference.

This has been resolved.  When I unzipped the plugin using the "unzip" program, the folder created by unzip had some kind of incorrect hidden extended attributes.  I manually created a "tidypics" folder in the mod folder and the copied (cp) the files from the folder that "unzip" created into the new folder that I created and tidypics has appeared in Tool Administration.  Thank you again for your help.