i accidentally discovered this recently so thought i'd post in case it ever helps anyone else

1996 TS (auto) - i dont know if i have an immobiliser (or if its anything to do with it) but sometimes when i turn the key nothing happens, (it IS in park - no clicking, no nothing) . The only way to get it starting is to turn the key the other way round. - ie pull the key out, rotate wrist 180 degrees, and put it back in.

strange i thought but just thought i'd share it

Means your car key is worn out by the sound of it :)

Nothing to do with the key being worn out, everything to do with the action of taking the key out and reinserting it. Yes, it is a key barrel and immobiliser problem.
Do a search before you pull it apart. Save some grief.

Hrmm interesting I get something similar sometimes, have also heard talk of people having heat issues and putting a relay in for the starter motor... next time I will have to try a remove/re-insert and see if it's related in my case.

Listen to the sound from the steering lock when you pull the key out. If it doesn't give out a healthy clunk, it may not start next time you put the key in. Had this problem, squirted CRC down the keyhole, healthy clunk returned and no more failure to crank. Don't know why, but it worked for me.

Wow, twice I had a similar issue. I thought it was my immobilise playing up. I was playing with the key immobiliser etc for a minute or two the first time and then it started. Probably more than a year later I stopped for petrol, and for 5 minutes failed to get the car started. I then waited for my old man to come and tried jump starting it, and it started first go.... something weird going on there, but looks like know I know the problem if it ever happens again.

Ollie