<p><a href="http://wincert.net/wp-content/uploads/2015/01/microsoft-windows.jpg"><img class="alignnone size-full wp-image-517" src="http://wincert.net/wp-content/uploads/2015/01/microsoft-windows.jpg" alt="microsoft windows" width="720" height="340" /></a><br />
These days system virtualization is used almost everywhere. Most of you who are reading this article have probably already used some of the well known virtualization applications like Virtual PC, Hyper-V, Xen Server, VmWare ESX or VmWare client etc.<br />
I will give you a tip on how to improve your virtual machine performance, especially if you&#8217;ve made a physical to virtual conversion.</p>
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<p>For instance, you&#8217;ve connected some devices to your PC, which you won&#8217;t use anymore. The device is removed but the driver stays for good.</p>
<p>Those &#8216;left-over&#8217; drivers can cause problems if they become enabled in the means of hardware conflicts or system starts to behave strangely.</p>
<p>Here is the tutorial on how to remove those drivers.</p>
<p>For a start we have to add environment variable:</p>
<p><strong>DEVMGR_SHOW_NONPRESENT_DEVICES</strong></p>
<p>To the Environment Variables dialog box.</p>
<p>Right click <strong>&#8216;My Computer&#8217; | Properties | Advanced System Settings | Environment Variables</strong></p>
<p>Click NEW under &#8216;<strong>System Variables</strong>&#8216; and add <strong>&#8216;devmgr_show_nonpresent_devices&#8217;</strong> environment variable to the System Variables panel.</p>
<p>When the dialog box appears type <strong>&#8216;devmgr_show_nonpresent_devices&#8217;</strong> in the <strong>Variable Name</strong> field and type &#8216;<strong>1</strong>&#8216; in the <strong>Variable Value</strong> field.</p>
<p>Hit <strong>OK</strong>.</p>
<p>Now to remove &#8216;non-present devices&#8217; in device manager.</p>
<p>Hit &#8216;Windows Orb&#8217; and type &#8216;Device Manager&#8217;</p>
<p>When Device Manager opens, select the &#8216;view&#8217; menu and choose &#8216;<strong>Show Hidden Devices</strong>&#8216;. Open any of the hardware selections, for instance &#8216;Disk Drives&#8217;</p>
<p>Here you can see greyed device drivers which aren&#8217;t currently in use. If you are sure that you won&#8217;t need those drivers anymore, right click on it and click uninstall.</p>
<p>If you need help, please post a comment and I will try to help.</p>