Those dastardly computers

I headed out solo today for my ride.  Had a route planned and pretty quickly ran into trouble when I found out that 116 was closed.  I'll admit there was a moment of "maybe I'll just go home", but I pressed on.  Decided to get lost in northern RI.  Literally get lost, very lost.  I started to just ride around, trying to stay on secondary roads.  Quickly I got sick of the hills (note the clips are going back on this week) so started to pick roads that appeared to go downhill.  Then started to follow the road marks from the NBW - I know from following their routes in the past that they are typically pretty and very low traffic.  I would stop periodically to check the map on my phone.  I have to say I was having a really good time, had no clue where I was for the most part.  Started to head back to the city when I hit 44 (part of this was hill avoidance) and felt good.  That was until I realized I was WAY too close to the brother and sister in-law's house in Cranston.  I feel like sometimes there place is a bit of a ride in a car, never mind on my phat whip.  Quickly made a course correction before landing in their living room in a puddle of sweat.  Then something happened, I don't know what, but I got horrifically lost in the Providence/Johnston area.  I've lived here long enough that it's a bit embarrassing how lost I got, it was like I hit a black hole or something.  Just when I was about to call for help I saw the public safety complex in the distance and headed into downtown.  Now this is where the confusion sets in.  I was hoping to ride about 50-55 miles and the computer on my bike put me at 30ish.  I thought it was weird but knew I was ambling along so called Joe and arranged for him and the kid to meet me in Colt State Park for a picnic.  I'll admit when I got onto the bike path I was a little bummed about my distance, I really felt like I had covered more ground.  Oh well, it was beautiful.  So I hummed along, weaving in and out of the bike traffic on the path.  I've learned that after about 35/40 miles on the bike I start to loose it.  Loose it like I have around mile 18-23 of a marathon.  Loose it like whipping skittles at strangers...it gets ugly and it happened.  I convinced myself I was getting the equivalent of a bedsore on my ass from the ride and was in need of urgent medical care.  Then just before I get off and toss my bike in the woods, the GU I just consumed starts to act and I begin to resume my sanity.  I roll into the park, call the husband who is just leaving home and we agree to meet at Haines Park.  Yes, I'm double backing but again that fucking computer has my mileage low so I'm kind of ok with it.  On the way back I decide that regardless of the final # I'm getting off the bike when I meet up with them.  Finally just as I'm approaching the entrance to the park, I can see them pull in.  The damn computer has a final count of 40 miles which doesn't make sense but there is no time to debate it.  We're off on the rest of the afternoon activities.  It's only when I get home and sit down to retrace my path that I confirm my suspicions.  The fucking computer was wrong.  I didn't ride 40 miles, I rode 58!  Next time I'm bringing my Garmin as a backup.