After doing a google search, I noticed that this seems to be a common problem with Dell computers. This is a fix that was offered on the Dell Forums that seems to work, but it will delete all previous restore points and you will have to create a new one. Other than that there is a Microsoft link at the end.
I'm guessing this is the common 'Restoration Incomplete' with event id 111? This is caused by corrupted restore points which can never be used again.
1) Right Click My Computer|Properties|System Restore|Check 'Turn Off System Restore'|Ok|Reboot the System
2) Right Click My Computer|Properties|System Restore|UnCheck 'Turn Off System Restore'|Ok
System Restore should now be working correctly.