prl_usb_connect.kext' was installed improperly and cannot be used

prl_usb_connect.kex was installed improperly and cannot be used

I had one problem, which was apparently with the usb drivers installed for Webcams in Parallels Desktop 8 for Mac. While I was attempting to solve this problem, a second problem occurred during update to the latest version of Parallels Desktop 8 for Mac. I suspect that the two problems are related. Any help in resolving the second problem will be appreciated.

Here's how these problems surfaced. For many months, I had not run Skype under Windows 7 on my VM. Skype had run well under Windows 7. However, when I tried to run Skype yesterday under Windows 7, Tools » Options » General » Video Options displayed an error message saying that it could not use any Webcam. Sorry, I didn't record the actual message.

I tried various workarounds to resolve this problem. None of them worked. Eventually I checked to see if there was an updated version of Parallels Desktop 8 for Mac to install. There was. I started the installation.

While installing that update, an error window displayed the following:
title bar = blank
headline text = "System extension cannot be used".
body text = "The system extension '/System/Library/Extensions/prl_usb_connect.kext' was installed improperly and cannot be used. Please try reinstalling it, or contact the product's vendor for an update."
button text = "OK".

Installation of the update ran to conclusion. After installing the update, all the Webcams worked in Skype on that VM. Still, I am left uneasy about the error window that displayed during the installation.