Do you have a Dell Latitude X1 ultra-portable notebook computer and find that it seems to run slower than usual at times? I encountered the same performance problem and found a cure for the mysterious sluggishness a few months ago.

The Latitude X1 is passively cooled. In other words, it has no fan to blow away the heat generated by the CPU the way mainstream laptops do. Instead the heat is distributed through the bottom of the case. You may have noticed how hot the bottom of the laptop can get.

Without a CPU fan, what happens when the processor gets too hot? It slows down. As a survival mechanism, the CPU’s clock rate will decrease in order to reduce the amount of heat being generated. Usually, the clock rate will be cut in half. As a result, everything will run more slowly. The X1 will do this even if it’s set up to always run at maximum clock rate and is plugged into a power outlet.

The solution to this slow down is quite simple: Cool the bottom of the laptop. This can be done in any of a number of ways including buying a laptop cooler (the rectangular-shaped plate with fans in it) or, if you have an external keyboard and monitor connected to it, flipping the computer over so that heat more quickly dissipates into the air. Leaving the laptop on your lap, desktop or blankets (for those who like to compute in bed) will just exacerbate the heat build up and keep the CPU running at less than full speed during moderate to heavy workloads.

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When accessing the settings dialog in VirtualBox on Ubuntu/Kubuntu 7.10 Gusty Gibbon, I would get the error, “Could not load the Host USB Proxy Service (VERR_FILE_NOT_FOUND). The service might be not installed on the host computer.” I found a variety of fixes from different forums and blogs so here’s a consolidated guide to resolve the issue based on my installation of VirtualBox 1.5.6 on Kubuntu 7.10.

1. Open the file /etc/init.d/mountdevsubfs.sh with your favorite text editor (be sure to use sudo or open as root so that you have write permission).

2. Look for the following comment:

   # Magic to make /proc/bus/usb work

3. Remove the hash mark, #, from the four commands (mkdir, domount, ln, mount) following that comment. The result should look like the following:

   #
   # Magic to make /proc/bus/usb work
   #
   mkdir -p /dev/bus/usb/.usbfs
   domount usbfs “” /dev/bus/usb/.usbfs -obusmode=0700,devmode=0600,listmode=0644
   ln -s .usbfs/devices /dev/bus/usb/devices
   mount –rbind /dev/bus/usb /proc/bus/usb

4. Save the file and run it with sudo (or as root) appending the parameter “start” to the end:

   sudo /etc/init.d/mountdevsubfs.sh start

5. Next, create a new user group called usbusers. On Kubuntu, you can do this with the User Management tool in the KDE Control Center.
6. Add your username, and anyone else who uses VirtualBox on the computer, to the usbusers group. Save the changes.
7. Open the file /etc/udev/rules.d/40-permissions.rules (again, using sudo or as root).

8. Change the following lines:

   # USB devices (usbfs replacement)
   SUBSYSTEM==”usb_device”, MODE=”0664″

   to

   # USB devices (usbfs replacement)
   SUBSYSTEM==”usb_device”, GROUP=”usbusers”, MODE=”0664″

9. Save the file.

Now it should work fine and you don’t even have to reboot.

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