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I have a Bluetooth dongle and I plugged it into my work laptop (a Dell Latitude D830). Windows detects the Generic Bluetooth USB or similar and then proceeds to go incredibly slow with a process, avp.exe¹, taking 50% CPU. The System Idle process is getting most of the other 50% CPU and the avp.exe process is only at Normal priority.

The machine doesn't seem to recover, so I had to turn the power off and reboot. Now, I haven't installed the drivers yet for the device, which I am doing now and I expect it to resolve the problem, so I am not asking how to fix this. I would rather know why Windows goes so slow in the first place. What is it trying to do and failing at so badly that it barely crawls?

¹ Part of Kaspersky Internet Security suite

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3 Answers 3

up vote 2 down vote accepted

I've seen similar behavior, in a USB parallel device. Leaving the device plugged into the machine would result in the machine taking 10x as long to reboot, and it would be 100% repeatable. Unplugging the USB adapter during the reboot restored the machine to normal speed; once it was booted into windows, you could plug it back in. The BIOS was having an issue with it, and once Windows loaded, it no longer mattered (because the Windows device driver took care of it).

As it is the internet suite that is eating up CPU time, I'd guess that it "thinks" that the device is internet-capable (has an IP stack) and it's attempting to latch onto the device and start monitoring any packets that come through. As the device really doesn't exist in windows-driver-land, there's probably just a stub entry there that Windows is using as a placeholder until the device drivers are fully installed. Because the "stub" isn't the real thing, your scanner is going berserk as it tries repeatedly to latch onto it but it is refuted at every turn. "Must...attach...and...filter!" it keeps screaming, but the stub sits there and is mute...so the cycle continues.

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That sounds very plausible. –  Jeff Yates Jul 17 '09 at 17:26

I have exactly this same problem and it is specific to Bluetooth. I've isolated it to the Windows 7 Bluetooth stack itself and not to the specific dongle. I did this by trying (quite simply) two separate dongles from two separate manufacturers. One was a Microsoft dongle that came with my Bluetooth mouse. The other was a third-party dongle.

In both cases:

  1. Computer running fine
  2. Insert dongle
  3. Computer grinds to halt..simple actions take minutes to finish
  4. Press ctrl-alt-del and it takes 60 seconds for the security screen to appear
  5. Choose "Start Task Manager" and again it takes 60 seconds to appear
  6. Kill BTStackServer.exe and BTTray.exe and also remove dongle
  7. Computer instantly returns to normal

I will do some more investigating but I think this is a bug in Microsoft's BT stack and we'll have to wait for a fix from them. Correction, we'll have to wait for them to acknowledge the bug, which will be never. Conclusion, we are screwed and cannot use Bluetooth devices with Windows 7.

My guess is that this is limited to particular hardware otherwise MS would have noticed by now. I'm using an Acer Aspire laptop.

I also have a hunch this could be linked to running Skype since Skype attaches to the BT headset service but again I'll need to do more investigating.

Let me know if you find any workaround or solution and I'll do the same.

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Do you have two CPUs?

My guess is that the hardware is causing some proccess to max out one of them. Good drivers will probably help this.

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Yes, it is a dual core. That would explain the 50/50 on CPU usage. Seems obvious now. –  Jeff Yates Jul 17 '09 at 15:03

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