After a busy week end for the car, (a 03 Sorento XE diesel auto), parked it on the drive after a journey of some 120 miles while opening the garage door, turn the key to re-start and it sounds like the battery has gone flat. Try it a couple of times, no good, starter motor just turns engine very slowly before totally stopping. Leave it for half an hour, still no go. Put a volt meter across the battery, shown charged even with headlights on. Try again, still no go, volt meter drops to about 8 volts. Try it several times and all of a sudden, starter motor works normally and engine starts. Re-start several times, no problem. Has this happened to anybody else and what was the problem?