Your problem might be the driver for the webcam. As it is harder to install drivers in windows 7 and 8 than in previous versions XP/98 due to the institution of Digital Driver Signature Enforcement, here's some step-by-step for you to go off of:
I. Find the correct driver for your webcam on the internet (it is most likely free on Lenovo's website; however, you could use the driver install disc that most likely came with your webcam).
II. Delete the current driver in Device Manager by following the instructions from http://www.pcworld.com/article/246041/how_to_uninstall_drivers_in_windows.html as are listed below:
Click Start, type Device Manager, and press Enter.
Find and double-click the category of device whose driver you wish to uninstall (for example, the graphics card would be listed under Display Adapters).
Right-click the device, and click Uninstall.
Windows will prompt you to confirm the device’s removal. Click OK to remove the driver.
After the uninstallation is complete, reboot your computer as soon as possible.
III. Follow the following instructions from http://sabrent.com/support/knowledgebase.php?article=14 as are listed below:
During boot-up, continuously press
F8 to get to Advanced Boot Options. Note: On some systems, you need to first press
F2 to go into Boot Menu, then press
F8 to reach Advanced Boot Options.
When the menu appears, use the DOWN arrow key to scroll to “Disable Driver Signature Enforcement.”
Continue the boot process.
After your computer has completed the boot process, please install the drivers per the included instructions.
IIII. This is how to work around the Driver Signing Enforcement. Then install the driver once your computer has loaded (Note: You must install the driver right after this process. If you do not, you will have to do it all over again.)
Hope this helps! (If it does, accept this as the answer to your question. Thx.)