T2958 continuous startup cycle

Recently, when trying to start the machine, it developed this problem: During booting it would flash this statement on the screen: autocheck missing. The machine would then restart and continuously repeat this cycle. Tech support suggested I place the harddrive into another machine and download files if I want to save them before using the restore disk. My son swapped it into another emachines but, of course, since the software on the 2958 harddrive is the problem, it remained. While replacing the harddrive back into the 2958, the power problem developed (see my other posting). Any thoughts?