Please help, dtx sys trey and other error

Hi all. I am having a problem with a computer at work. My boss's computer would not let him sign in to our dental program. So I tried deleting all history, basic stuff. But when hitting the start button, it would flash and disappear.
I ended up doing a hard boot and the screen stayed blue. After 30 mins of it uploading the icons, I was able to get it in. Is something going to happen to his computer again? The error read...dtxsystrey and the other was not enough memory.

Thank you
DJ