Click on the Start button\then click on Run, and type: "regedit" (no quotes) and press Enter... browse to the "don't load" registry key (HKEY_CURRENT_USER\Control Panel\don't load) and look in the right pane for the REG_SZ value named "wscui.cpl" (Windows Security Center User Interface) and delete it. All the values in the don't load key are prevented from loading... so delete the wscui.cpl value to make the Security Center load... Restart the computer if it doesn't immediately appear in the Control Panel.
The security warning messages must be due to the antivirus configuration, if it's programmed to ask the user for actions to take and not programmed to work silently. It could also be the antivirus deffinitions are outdated, antivirus is disabled, or there's some security defficiency. After the Security Center loads, check it and follow any recommendations it gives. If it turns out that there's some security issue, resolve it and scan your system.