Autoprotect is off...will not allow me to turn on

Auto proetct is switched off, legend says 'at risk'.  When I click the "Fix" button, nothing happens.   When I go into settings and configure on auto protect the suto protect box is unticked.  When I tick it, nothing happens.  Will not allow me to change anything.  Here is my system info:

 

OS Name Microsoft Windows XP Professional
Version 5.1.2600 Service Pack 3 Build 2600
OS Manufacturer Microsoft Corporation
System Name TIM
System Manufacturer Dell Computer Corporation
System Model Latitude D500
System Type X86-based PC
Processor x86 Family 6 Model 9 Stepping 5 GenuineIntel ~1294 Mhz
BIOS Version/Date Dell Computer Corporation A10, 6/29/2005
SMBIOS Version 2.3
Windows Directory C:\WINDOWS
System Directory C:\WINDOWS\system32
Boot Device \Device\HarddiskVolume1
Locale United States
Hardware Abstraction Layer Version = "5.1.2600.5512 (xpsp.080413-2111)"
User Name TIM\Administrator
Time Zone Mountain Daylight Time
Total Physical Memory 1,536.00 MB
Available Physical Memory 839.93 MB
Total Virtual Memory 2.00 GB
Available Virtual Memory 1.96 GB
Page File Space 3.35 GB
Page File C:\pagefile.sys

 

Please advise...Thanks!