I went for a chat support provided by emachines on the issue.
Even though my warranty is expired, the agent-bot did provide an answer:
Either it is the driver
, or either I have to do a system restore and the problem should be fixed.
However, originally, I used to have 64-bit installed on this computer, then the system crashed and needed new HD.
The shop put win 7 32-bit on it, which did not come with any software to deal with the webcam.
Therefore, I really don't see how a system restore is going to help me.
What is your opinion?