Turn the key no response !! 2000 Boxster base

[Frank Porro]

I replaced the battery, I replaced the electrical portion of the ignition switch. As to the key, the cylinder it is not acting up, or difficult to turn etc. No electronic flashes or other difficulties.
So, why is turning the key so unreliable? Nothing happens, all I see is dash lights, no noise no response.
Thought I had it fixed by closing the windows, top up, and locking the doors with the key in the door lock. It worked!! ... then it didn't!
I have learned not to do anything unless you disconnect the negative side of the battery to avoid a check engine light turning on.
I do not have a working electronic key transmitter so I only use the regular key that I have.

So back to why won't it start??
Can the central locking immobilizer be so inconsistent as to work on any given try and then not the next? I know the immobilizer has a fuse, could this still be the problem?
As electronics is not my strong suit how careful must I be with the immobilizer unit?
Is there another area I need to check?

There are many posts on the forum about this issue, am I missing something?

Thank you for any advice!
Frank