High CPU usage after resume from standby

I am running Win XP (SP3) on a machine with about 3.2 Ghz processor and 3.5 GB RAM. When I resume from standby, Task Manager shows about 40% CPU usage on the Performance tab. This doesn't map to the info on the Processor tab, which shows about 99% system idle process if I AM using other programs (like a web browser) and shows about 60% System Idle Process and 40% "System" process if I am NOT using any programs. In neither case is there a process or a set of processes that is using 40%. Services.exe and svchost.exe are listed at 0% usage. The number on the Performance tab may go up if I've done multiple resumes from standby without a restart in between; not sure about that because I haven't tested that recently.

If I do a shutdown and start up, or a restart, the Task Manager shows 0-1% CPU usage.

I have recently done exhaustive scans for malware and they were all clean. I have also recently reinstalled the OS onto a brand new hard drive, for unrelated reasons (hard drive hardware failure). However, I don't think the reinstall or the new hard drive is causing the problem because I had the exact same problem before I replaced the hard drive and reinstalled the OS.

I have a second PC with basically the same hardware and software, and it does not exhibit this high CPU usage statistic when resuming from standby. So maybe it's some device on the affected PC that's taking system resources when resuming. The main hardware difference between the two PCs is that the affected PC has a backup hard drive while the unaffected one does not.

Two questions:
- Is this high CPU usage statistic correct, i.e. providing info about what's really going on, given that it doesn't match up with what the Processes list shows? Can I investigate that further?
- If it is correct, what can I do to diagnose or fix the thing that may be causing the high CPU usage after resuming from standby?


Thanks for any ideas,
Roger

This is a problem that had plagued me for nearly a decade. I tried all the suggested fixes on the net, such as resetting the hosts file, complex tweaking of registry entries, none of that mattered.

I gave up trying to solve it and instead I always depended on a work-around fix. After resuming from hibernate or sleep I would issue a "DEVCON RESCAN" command (caps not required) from the run prompt or even from task manager's file > new task (run) prompt. Or more usually, from a simple bat file and a click to a shortcut to it.

Then one day the problem miraculously disappeared. I narrowed it down to the fact that for once I resumed from a hibernate without having my USB media-card-reader plugged in. It finally made sense, as I was having boot-up problems on a notebook too whenever I would leave a USB terabyte drive plugged in.

Remove any removable media devices from your USB ports. Leaving a DVD or CD in a drive might even cause it.

If that hasn't fixed it for you, then depend on the "devcon rescan" work-around fix after resuming from hibernate or sleep. (It's the same as going to your device manager and rescanning for hardware changes.) With Windows remembering your last run-commands issued, it's usually a simple matter of just re-selecting it from the drop-down list. (If you haven't tweaked your system to clear that history, that is.)

Just to be sure, when you are looking at the Processes tab, do you have the box checked for Show Processes from all users?

Thanks to both of you for your suggestions.

Re. seeing processes for all users -- I have unchecked that, but still can't see anything that's using CPU. E.g., right now Performance says about 65% of CPU is used, and the processes that have high CPU assigned to them are just System Idle Process (about 60%) and System (about 40%).

Re. having other devices connected -- I hadn't thought of this. But right now nothing is connected except my hard drive and backup hard drive. The two DVD drives are empty. Several USB ports have useful things in them, like my mouse and keyboard. If it's one of them, or the backup hard drive, that is causing this behavior, then disconnecting them is obviously not a practical solution.

Re. devcon rescan -- This sounds like a reasonable workaround. I'm having trouble getting it to work though. I tried running it as a new task in Task Manager, and at Start | Run, with the same error message (Windows cannot find devcon). I went to microsoft and downloaded it. Devcon.exe wound up in a temp folder that the Task Manager and Run still could not find. I copied it to a location that I accessed from the DOS prompt and gave it the command "devcon rescan." It said it was scanning for new hardware. But afterwards, I still have about 65% CPU usage reported in the Task Manager. At this point I'm assuming it ran correctly from the DOS prompt but did not fix the problem.

Any other ideas?

Thanks again,
Roger

Just for testing purposes, see if you have the same problem with the external usb drive unplugged from the pc. If the problem goes away, try plugging the drive into a different usb port and see what happens. There is a chance that the port is going bad. You might want to try the same for any other usb devices that are plugged in.