It should work can you try (Ctrl + shift + 6) together or press ctrl keep holding it then press shift keep holding both and then press 6.
Should work, I checked again.
I'v egot it to work but don't ask how! it's a case of continually pressing all four buttons until the trace stops.
Thanks Ankur for your help.
It's the same sequence that breaks you from a connection, you should be able to easily do it with practice(and you will get lots of practice telneting into your various routers and switches).
The 6 is not necessary, it will drop you out of the traceroute or ping seqence without it.