Hi Mostafa,
First, you should not have AVG and MSE installed (and especially not running) at the same time. Choose one and remove the other. For now, since MSE seems to be installed, leave it there and uninstall AVG if it is still installed. I hope we can enable MSE somehow (and we will give it a good try), but if it was done by an infection, that may not be possible until we remove the infection by some other method.
Go to Start / Control Panel / Administrative Tools / Services and scroll to Security Center and make sure it is started and set on Automatic. If not, change it to Automatic and then start it. Hopefully it will start and remain enabled. If you can't start it, click on the Dependencies Tab and check each of them to make sure they are both Automatic and started (and if not, do so with them as well and then return to Security Center and try again after fixing the dependencies). If all seems fine, then recheck security center to see if it is now running. If not, we're going to try to bypass it to at least try to get MSE working without using it.
Now go to Start / All Programs / Microsoft Security Essentials and double-click to open it. First, click on the Update tab and update it so it is current. Then go to the Settings Tab and click on Real-time protection and make sure you check all three boxes on that screen. Then click on the Home Tab and see if it says real time protection is active and definitions are up-to-date. If it says it is off but offers a button to start it, press that button to see if you can get it to start. Note we are doing this directly with MSE and not using Security Center in case the problem is there and we can get MSE to work independently. If it works, great - but we're still nowhere near out of the woods. If not, we'll have to do the best we can with what we have.
If that doesn't work, try to boot into safe mode (repeatedly click the F8 key while booting and go to safe mode with networking). Then let's check some of your system files:
Go to Start / All Programs / Accessories / Command prompt and right click on command prompt and click run as Administrator.
Type sfc /scannow and enter and let it run. It will scan and try to fix some of your system files. Hopefully it will complete with no corruption it could not repair (if there is such corruption post back here or try to analyze it to find the problem file(s) using http://support.microsoft.com/kb/928228. Try to attach the report (you may need to copy it to your desktop before it will permit you to attach it) here so we can see if they can be repaired with good copies from the installation disk or in some other way (unless there are too many).
While in Command Prompt, type chkdsk /f /r and enter and let it run. It will want to schedule itself to run at the next restart. Answer yes and then reboot to run the program. It will scan and try to fix any corruption or bad sectors on your hard drive and mostly remove that as a potential cause.
If that doesn't work, then please post any error messages from the Event Viewer concerning Security Center or Microsoft Security Essentials (Start / Control Panel / Administrative Tools / Event Viewer). Here's how to use Event Viewer: http://www.petri.co.il/vista-event-viewer.htm. Look in the System section and the Application section. When you find them (there WILL be some), click on each for more details and then click on the Details Tab and then copy what is there and paste it to your next reply. If they are all the same, one will do. If they differ in ANY way, copy and include those that are different as well.
If that doesn't work, try a clean boot http://support.microsoft.com/kb/929135. If the problem goes away then it's just a matter of tracking down the culprit causing the problem. Follow the procedures in the article. Once found, delete, remove, deactivate, or uninstall it. Once done be sure to reset Vista back to normal status as explained in the procedures. If the problem occurs in clean mode then just restore the system to normal status and reboot - this solution is not going to work.
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Temporarily at least, stop using your email program (close it) or website, and stop browsing the web except to go where necessary to get the files we need (as noted below) or to visit this site - and go only there. Otherwise stay on this site and check periodically for replies (after you have done what follows and replied). Close IE when not in use and open it only to check. I want to do whatever we can to avoid any infection (or any more infection) entering while you are lacking protection. If you decide to use the internet anyway, you do so at your own risk and it may well make things worse than they are now - but that's up to you.
I suspect you are infected and that may be why you are having troubles enabling it (if the above didn't do the trick or identify the problem) - but hopefully the following will help identify the infection if that is the case. I suggested this before, but I've now broken it down into separate steps.
Please download, update, and run a full scan using Malwarebytes:
http://www.malwarebytes.org/mbam.php. It will produce a report. Please save it to your desktop (or take a screenshot or slice image of the result page and save it as a .jpg file) and attach that to your next reply.
Please download, update, and run SuperAntiSpyware:
http://www.superantispyware.com. It will produce a report. Please save it to your desktop (or take a screenshot or slice image of the result page and save it as a .jpg file) and attach that to your next reply.
Please download, update, and run Hijack This:
HijackThis - Trend Micro USA (the full release, not the beta version). It will produce a report. Please attach that report to your next reply.
After we see these results (as well as all the other attachments and results we've requested above, we'll determine if we need to call in a security expert for assistance (which I strongly suspect may be the case).
I hope this helps.
Good luck!
P.S. What do you mean by "Hack Tools" and why do you suspect them? Do you have or have you ever had anything like that installed on your system?
P.P.S. I know this is a lot and will take time and effort, but it's the only way I know to identify the problem so we can find a solution to it. I urge you to do EVERYTHING requested - print it out and check off each item as you go along just to make sure you don't miss anything. And PLEASE attach all the files, images, and reports requested (and I know there were quite a few). We need that information to find the problem and help you. We'll do everything we can to assist you, but we need you to help us as well by following all these instructions.
