onegoodmove

I recently received another email from Igor. I hadn't received any for a time and the few I did receive were infected with the Klez worm. He finally got some help from the Norton's and they found a worm in some attachment and quarantined the sucker. Igor says, "Lets hope that is the end of it but frankly I don't think so, and he signs the email with "Igor, the worm slayer."
More interesting is the problem he sent me to solve. He didn't tell me but I'll tell you the last time we corresponded he was still working on it himself. So here is the mission if you choose to accept it. White plays 1 e4 and on Blacks 5th move he plays NxR mate. Construct a legitimate game from this bit of knowledge.
Just to be clear 1. e4 ... 2. ... ... 3. ... ... 4.... ... 5. ... NxR mate.
I wrote Igor back to verify the puzzle was correct since my head was beginning to ache. He confirmed that it was. He further said that "he was told that without 1 e4 the solution was easy not that I have found it. So the obligation to 1. e4 does make the solution somewhat more complicated. I was also told that Botvinnik and Tal spent an hour on the train trying to solve this one and failed. Sell it for what I bought it." If you find a solution either to the original or the easy (ha ha) version please post a comment, for I fear there will be many more headaches before a solution is discovered.

Update: I have the solution. Alas, I didn't solve it but was told what it is. If you are tired of trying email me and I'll send it to you.