Hello, I have noticed this behavior few times already.
I'm switching window from Safari to UltraEdit, by using AppleKey+Tab, and I am going to comment out some line of code with //.
For some reason the focus has been in the project view and it instantly tries to change the name of the current file to //, which of course fails.
Even if I notice that and press ESC, it still does some unexpected changes: It removes the execute rights to entire directory and starts claiming that all my files have been deleted.
Luckily nothing is deleted and situation can be remedied by giving chmod a+x DIRECTORYOFTHECURRENTFILE in the terminal and reopening current file.
It's quite unexpected and annoying behavior. If the rename fails, it shouldn't do anything and it should keep the original name.
I've reported this to IDM, but just wanted to post a fix/help if someone encounters the same problem.