98 Trans Sport/Montana - no start

This problem is occuring for the third time now.

Symptoms:
Car is driven as normal - no problems. Get in to start, as ignition switch goes from off throught "on" all dash lights indicators go on, but as key enters "start" everything goes dead. All electrical is gone. If I go back to just "on" the shift indicator for "park" blinks dimly.

If I jump start the car everything runs fine.
When I turn it off, everything will be dead again on attempt to start.
Jump start again, everything is fine.
Turn off and on everything is fine.

The first series of times this happened I took out the alternator to replace it but it tested fine. After puttining it back in, I had no proble for over a year. I thought maybe bad connection somewhere.

Now, about a month ago same thing happened all over.
Took it to a shop and they found that there was a dead battery cell, low voltage.

Replace the Battery and all is ok.

2 weeks ago same problem all over. After the second jump start I did on/offs and it would always restart. Took it to the shop that replaced the batt and no charging system or battery problem found. Everything working ok.

Yesterday all happens again. But now will not restart on its own after jumping it.

Took the battery out to get it tested and that is ok.

Haven't put it back in yet. I need to examine the wires to look for crud.

Anyone have similar problem? Is there a gremlin under my hood? Bad "computer"?

Help!!!

This has ALL the looks and sounds of dirty/corroded battery cable connectors....a common , invasive and "it can't be that" (but it is) problem...so unless you are positively categorically definitely certain that these connectors are really + completely corrosion free and fully tightened ...check again. Check the OTHER end of the cables too.

...Unhappily, I have no other clue.

Thank you for the info.
When I put the battery back in I wire brushed the terminal and the cable ends.
On observing the cable ends it looked like there was a lot of "Plastic" and it looked like there was a ridge on the plastic that might prevent the terminal from making good contact so I trimmed it off and wire brushed the cable terminal better.
It looks like the terminal is copper actually and was oxidized like an old penny. I shined it up a bit and hooked it all back up.
Ater that it started up fine, so time will tell if this is the fix.

One previous time, like I wrote in my original, it was a year before it occured again.

But by all appearances that was the fix.

Thanks a bunch. That probably saved me a lot of $$$$

Glad it worked: I'm sure your problem is solved.
BY the way, a LOT of similar cases end up with one changing the battery...and miracle, problem solved....but in fact, the act of disconnecting the old battery, and in the making, clearing some of the corrosion, and connecting the new battery makes a new start...but putting back the old battery then would have given same result.
Most of the time, this happens after the number of years that make that a new battery is almost due anyway, so that the money "expensed" for that "problem" would have been required sooner or later anyway, but the lesson here is that battery connexions are the most sensitive point of the electric system, so look ..and insist..and scrape connectors in the first place, then you can change the battery when it is required only.
5-6 years on a battery is normal.

I had the exact same on my 97 Trans Sport last year. It was the ground cable. Once I took it off (which was chore in itself) I cleaned up the cable and ground point and no problem since.