If you mean that it cranks (starter turns engine over) yet doesn't start until you remove the key from the ignition, then re-insert the key and it then starts.....I'd say the problem is a bad immobilizer antenna ring. It's a simple part to replace, it's the lighted ring that goes around the ignition switch. That won't cause a "no crank" condition however.
When this happens, are there other newer cars keys on the same keyring? Believe it or not, there's been reports where another car brands key near the ignition switch caused intermittant "no starts" on newer Volvos.
There's other possible causes if it's a "no crank", could be a sticking or "slow" starter relay. There's a TSB about checking the battery B+ cable in the front, engine fusebox for corrosion but I'd assume your dealer knows that and checked it?
If nothing else, see if someone at that dealership can try duplication the problem by driving it home if need be. I have to do that on occasion for troublesome cars and it usually helps as once duplicated, the tech should be able to locate the cause. Have they tryed contacting the tech hot line? Might take a bit more persistance on your behalf.