I have an error with Windows Security Centre on WinXP..help?

[torrenter]

I have a few problems with my computer that I think have arisen from me deleting the wrong registry keys.

1) From the start menu, if I click for the Control Panel or My Network Places, it opens My Computer.

2) When hovering my mouse over my desktop items, their location does not list anymore, such as "Crogram Files\..."

3) Lastly, whenever I open Windows Security Centre, I get the following error:

The Security Centre is currently unavailable because the "Security Centre" service has not started or was stopped. Please close this window, restart the computer (or start the "Security Center" service, and then open the Security Center again.

It doesn't show me my Firewall, Automatic Updates or Virus Protection status.
Plus, the option for "Change the Way Security Centre alerts me" is no longer active a.k.a - dead link!

It's got to the stage now where I don't see the full effect of deleting certain registry keys until much later. It's annoying as I only delete keys with the name of previously installed applications in them!
I would really love to understand this incomprehensible registry, so if anyone knows how I could solve the above problems or tell me how I could have caused them that would be brill.
Thanks in advance.

 

[rlcowboy]

Start Services

Try clicking start>run>C:\WINDOWS\System32\mmc.exe. Then File>Open>C:\WINDOWS\System32\Services.msc(just browse to the System32 folder and click on Services). Go to Security and start the service(if it is disabled right click>properties>enable(in the drop down box) Startup Automatic> Start the service

 

[Peddant]

Have you tried system restore ?

 

[torrenter]

Thank you so much for your help rlcowboy, this actually worked. I thought I had seriously screwed up Windows, and thought someone would just say restore the whole computer from a fresh. Would you know how the Security Center could have turned off? I mean I completely uninstalled Norton/Symantec and deleted all the left over relevant registries before installing McAfee as a new alternative, but can't tell when it happened....