If you run the Second Life Development Viewer “Uninstall”, and at the end of the process it says “There are files left in the SL program folder, would you like to delete them?”, it not only deletes the files in the program folder, it also deletes the files in “Application Data” and “Local Settings, which means it deletes your settings, your entire chat history, any files you have in the “Application Data” SL folder for testing UI skins, and so on, but it deletes the files in such a way as to bypass the recycle bin. I do not like it when programs delete files in such a way as to bypass the recycle bin. I have my OS set to put deleted files in the recycle bin for a reason. Programs mistakenly deleting nearly 7 years of chat records is a good example why. The problem with deleting file other than those in the SL program folder might already be fixed, but I’ll wager that the bypassing the recycle bin problem is not.
After seeing that the files were not in the recycle bin, I tried a system restore to yesterday. That did not restore the deleted files.
There’s no reason for programs to delete files permanently like SL does.