2004 Aveo will not start without Putting and holding all the way in gear

My wife's 2004 5 speed hatchback sometimes will not start (starter will not even engage) unless you put it in gear and hold the shifter all the way in gear. Today when she stopped @ the gas station it wouldn't start and even this didn't work. While on the way to rescue her I had her hold the key on while she moved the shifter around (slammed around would probably be a better term) and it started. I'm assuming it's a sort of safety switch that needs adjustment or replacement but need to know the name and how to adjust or replace to repair.

Any help would be awsome

Thanks
Dave

There shouldnt be any switch at all in the shifter other than for the reverse lights...

I don't believe it is on the shifter but on the transmission itself....

The only sensor like that on the transmission is for the shift light, that goes off if the car is in 1-4 gear. Other than that as far as I'm aware of there is no other sensors

I thought the interlock switch was in the clutch. My 5 speed will not turn over unless the clutch is in or the car is in neutral.

I know it sounds odd and I know it doesn't jive but I'm telling you from a year of experience, that when it does this it will only start with the Shifter pushed firmly in gear.... :p I'm confused myself that is why I got on here because what you guys are telling me is what I know to be fact from dealing with previous cars and trucks
Also this car doesn't appear to have a shift light (or at least it has never worked)

Maybe the shift light is only on the ecotec. I haven't taken a good look at the e tec or the e tec trans. Maybe daox can help?

So you're saying *usually* it starts normally regardless of where the shifter is (even in neutral)?

I've never heard of a manual car that requires you to be in gear to start the engine. Someone with a wiring schematic could confirm whether there's a "non-neutral" circuit in there. Don't expect you'll find one.

I'm tempted to think that when the problem happens you're also pushing down harder on the clutch pedal -- even unconsciously -- while you're pushing the gear shift. Which would suggest a clutch switch issue.

But I'm not going to argue the point with you! You seem adamant it's shifter-related.

I retract part of my earlier statement-- my 5 speed will only turn over with the clutch engaged. In neutral and the clutch disengaged results in nothing happening when the key is turned.