Just an update about my strange issues.
I had the chance to verify that they also took place in Leopard, so not a Sorbet Leopard related issue.
After several tests, ram modules tests, kernel panics errors (each one more serious than the previous one) , it looks like after having the ssd formatted (using target disk mode) everything works properly again. Even , for a while, I thought thay my mac was fried, because it could not even boot.
To be honest, I'm 100% lost about what happened, because I don't expect that kernel panics (related to cpu, ram, etc) could be solved with a simple ssd format, so I'll keep my fingers crossed for a long time , without knowing what to expect.
In addition, as it currently works perfect (or at least it seems so) , I'm going to leave it with the current 1,25gb ram installed, and don't even try it with 2gb (what it had when all that mess started). If it works, don't touch anything