I recently had install Win XP MCE 32bit on a new hard drive. Frequently and sporadically I get the above message from the Windows Security Icon in the system. It says to click the message ballon to fix the problem. Clicking the ballon takes me to Windows Security Center. It shows Defender as being off. Within a few seconds it shows as turned on, without any action on my part. I use AVG Free, the same as before my old hard drive died with no problems in the past and my wireless router is well secured.1 person got this answerI do too