This particular error indicates that a level-1 Interrupt was issued during the power-on self-test.
Interrupts are the way the computer prioritizes its activities. For instance, say that your computer is on and busy doing something (the cursor is shaped like a watch). You reach for the mouse and move it. If the system was really busy, you would not see the cursor move since the computer was doing something else and couldn’t update the position of the cursor on the screen.
Interrupts take care of that situation. Mouse movement is allowed to “interrupt” the current activity by requesting a level-1 interrupt. When that happens, the system stops what it is doing, moves the cursor and then continues where it left off before the interrupt occurred.
Level-1 interrupts can be issued by the mouse, keyboard and monitor.
There are a total of 7 interrupt levels. If more than one interrupt occurs at once, the interrupt with the highest number is handled first.
What to do
The System file is probably corrupted, try re-installing it. If that fails to solve the problem, you are probably having a hardware failure. The System file can appear to be corrupted because of bad RAM or a bad disk. These possibilities can only be evaluated with certainty by an Apple Repair shop. Consider having your system examined if you don't feel capable of doing it yourself.
