L502X Freezing on Start Up

I've got a 2011 manufactured L502X, and within the last two days I have begun having issues at start up. Everything goes normally until the initialization seems to be complete, then the screen completely freezes. The cursor won't move, the clock stops, and ctrl-alt-del has no effect. I have to turn off the computer using the power button. I have run two hardware checks and two system restorations, with nothing reading as failed and thus far no solution. The computer often starts properly upon the second initialization and also boots well in safe mode. Does anyone have any solutions for this problem?