horrible ifr training x-c

Okay, I've been doing this IFR training thing now for a
few months, flying once or twice a week, and it's been
going pretty well. I've not really had any trouble with
the knowledge part (self studied for the written and
got 95%) and have been doing nicely with the skill stuff
as well, getting the holds, ndb approaches, everything.

So on Sunday I have my requisite X-C with my instructor,
and, wham, I feel like I totally unraveled. Just one mistake
after another. Sloppy approaches, forgetting to swtich
tanks until the aileron to keep the plane level is
unmistakable, not identifying stations, and what bothers
me the most, is confidently navigating right down the
center of the wrong airway. How, you ask? Simply by
putting my finger on the map 3/4" from where it should
have been, and then reading off the headings, intersections,
everything incorrectly from that. I'm sure my instructor
knew what was going on, but I only found out when ATC
kept asking me why I was so far off the airway. (these
airways were close enough in distance and angle that my
error only became obvious to radar after many minutes
flying.)

We were safe, the whole time. I was under the hood, we
were on top in VMC enroute, and my instructor knew what was
going on the whole time, but the whole episode was
rather unnerving.

It's just all too easy to see how just a simple mistake
or two can be deadly in the clouds.

So. Anybody else have a bad flight that made them
question their instrument rating worthiness?

-- dave