Problem with file copy

[lugosi]

I am having a problem with copying files. Sometimes when I press CTRL-C to copy a file, the program crashes (I am using 2008.06c version, by the way). Other times, when I go to paste (CTRL-V) the file, I get a copy dialog.
Now, in some of the threads that I have read already, it tells how to get rid of that dialog (use no ask Shift+F5 and no ask Shift+F6), but if I do that, I no longer get a warning if I am trying to paste a file over a file of the same name that already exists.

Is there something that I should be doing to fix this?

Thanks in advance for your help