This is just one thing you can try. Right-click start, properties, customize, advanced tab, control panel, display as a link. It should show up in the start menu. Click Folder Options in Windows Explorer, view tab, scroll down to "ShowContol Panel in My Computer", tick the box.

 

It would be a good idea to scan for viruses and malware, spyware, etc. 

Yes, that message usually means that some malware has put entries into the registry to stop you accessing Control Panel ( and maybe more XP functions)

 

You will have to go to the HijackThis forum here and post a log so the experts there can help you.

 

http://www.dellcommunity.com/supportforums/board?board.id=si_hijack 

 

Read the red link at the top and then post your log on the forum with a description of your problem, plus the Model of Dell you have and the OS Version.