Please can you be more specific about the issue?
Do you mean that you cannot open McAfee SecurityCenter. If that is the issue please let us know the following.
1. If you have done a system restore or not.
2. If you have an Virus Infection on your computer.
3. The version of your Internet Explorer
4. The Operating System on your computer.
Added to Amal 's quetion : : : : :
Check the date and time, if it is not correct, correct it and restart the computer
What is the type of Operating system ? ( Windows XP / Windows VISTA / Windows 7 )
What is the type of internet connection ? ( DSL / Dial-up / Cable / Wireless / Satellite )