Interrupts and DPCs
On Windows NT-based systems Process Explorer shows two artificial processes: Interrupts and DPCs. These processes reflect the amount of time the system spends servicing hardware interrupts and Deferred Procedure Calls (DPCs), respectively. High CPU consumption by these activities can indicate a hardware problem or device driver bug. To see the total number of interrupts and DPCs executed since the system booted add the Context Switch column. Another sometimes useful metric is the number of interrupts and DPCs generated per refresh interval, which you see when you add the CSwitches Delta column.