I use windows 7 bt i face a problem with this.My system says turn on windows security center service when i try to do it says the windows can not be started. can any1 suggest?????

Malware is the usual cause of that. What protective software ave you got?

I have been using Avast free antivirus...........

That is antivirus only. What antimalware software do you have?

i need product key windows 7key

i need product key windows 7key

You will have to buy it from Microsoft.

yes it is the cause of a malware! test malwarebytes

try to use an internet security software. it has a malware remover or try to download a malware remover software but be careful maybe that thing has a virus with it. for me i suggest you use avg internet security.

actually i dont ve a antimalware soft. which 1 will suit best for win7.

Avira is suitable for all I think.

The original poster asked for antimalware software. Avira is antivirus software, not antimalware software!

a similar problem persists with i8 with windows 7

update your anti virus....

you should activate windows 7 and put microsoft security essential make it update then scan full system your probs will be solved