Urgent: Car Wont Start.

[TyleR34]

Okay I don't know where to put this but I thought POSSIBLY its a common problem for skylines (R34) so thought it was worth a shot.

Recently I upgraded to a heavy duty battery before I installed a fairly decent sound system. All was running fine.

The other night I went for a drive parked for a second didnt turn the car off but turned the headlights off, when I turned the headlights back on the car stalled in neutral.

I thought this was just the alternator not upto scratch with the sound system so I turned all my music off.

The next day I got in my car all was good without the music on, I went to tafe. Went to lunch got in the car and my car didn't even click over, turned the key a few times then bam started like normal.

This happened again as I got home then went to go out but this time the doors wouldnt unlock or lock with the key. I opened the car with the key, started her up after trying the key a few times then decided i probably shouldn't go back out so turned off the car and the doors locked as normal with the remote.

Any ideas?!

Thanks.