yeah its your ignition, there is a short and im betting it has to do with something between your ignition, start position switch, the alarm, and starter.

I would first check all the fuses, internal box, and external box. Then go check the starter make sure all the connections to it are in good shape and accounted for. If all thats good then the hard stuff begins, might as well start taking apart your dash for the ignition wires to the key switch. Basically you need to trace all the wires running from your ignition switch ALL OF THEM. I really think it is the wire that hooks up to your alarm that whoever installed on the car didnt make a good connection or ground for it. So either the positive from the alarm is hitting bare metal causing your ignition to be a double negative in current flow which would be really bad, or your alarm system keeps resetting itself because the ground is disconnected but still brushing up against its connection.

If its not just a short or open circuit, I think you should just take it somewhere because when this happened to me it was my ignition switch, and they had to replace it. The funny thing is, I was doing nothing when mine when out on me and then I went to start it the next morning and it wouldnt crank and the key wouldnt hold in the start posistion it would attempt to start by turning on all my gauge cluster lights and warning lights but that was it so yeah goodluck man that was my advice hope it helps