On the one hand, this problem is often caused by a malware infection. You should first run a malware scan to check if there are any active threats in your computer. Doing this is possible using Malwarebytes' Anti-Malware as a recommended solution or any other anti-malware application.
On the other hand, it is possible that your operating system faces corruption among registry or files. A system repair is recommended if you have the installation CD.
