You should be able to create a start-up log file, then view it to see what is failing to load, if it is indeed a software issue, and go from there. I have had several E-Machines in for repair for this kind of problem. Sometimes bios settings can cause it, sometimes an added card in the wrong slot causes PnP to get tied in a knot. Other times bad bios chip/ flaky bios firmware. On an odd occasion, a dodgy power supply can also cause it.
To rule out any obvious hardware/ bios problems, get a copy of a linux live bootable CD and boot off the DVDROM drive. If the machine boots and plays nice, then at least you will know for sure what you're dealing with.