There is a small window that has  appeared in the corner of my screen saying "software download complete" with two choices: "install now" or "Install later". I can't close it, and I don't remember downloading anything. I tried restoring the computer to a prior restore point, but it is still there. Is it a virus?

I am using windows 7 and Microsoft security essentials. Nothing has shown up currently in any virus scan, but it did catch a trojan virus awhile ago. It said it stopped it.
I have Windows 7 with Windows Mail and it keeps asking me for my username and password for all 10 e-mail addresses that i am using.  It is not my anti-virus nor my firewall as i am using Microsoft Security Essentials.  I have tried deleting and then adding back on these e-mails to no avail and i have also tried uninstalling Windows Live Essentials and reinstalling it but the problem is still there.  When adding in each e-mail i made sure to check 'remember password'. What else can i do??  Thank you.
Will there be daily updates for windows security essentials after April 2014 for windows XP?
Will windows security essentials still work after April 2014 on a computer running XP?
Thanks
Wondering if  Microsoft security essentials is perhaps not compatible with my macbook air. 

It seems as if someone has gained access to my contacts and has sent them an ad from my account. I have a macbook air and I tried to download microsoft security essentials as provided free by hotmail but it did not download. i am a lost as to how to deal with this problem. Quite computer incompetant here. Any help woould be appreciated.
Using Windows Live Mail Windows 7 64bit, FIREFOX, latest version receiving an error message when I click a link in Windows Live Mail.  A pop-up says "there was a problem sending the command to the program" Believe I removed ALL antivirus programs before installing Windows Security Essentials this morning. DH installed on his this am, too, using Vista and Windows Mail, removed same Avast I was using and no problems with links.  I can copy/paste the link and put it directly into Firefox and it works.   Do NOT want to use IE for my browser.
17. May 2012 · Comments Off on I used microsoft security software, but no avail, my hotmail send out e-mail and I can`t stop it. I check for root kits, malware and trojans, found nothing · Categories: Uncategorized · Tags: , , , , , , , ,
I get other people e-mail that meant for someone else, not in my household.  My computer is sending out e-mail to company and retails that I do business,  but I am not the one that sending it out.  I used Microsoft security essentials, Sophos`s root kits and malware- free.  I can`t stop it.  But may think the one link is the e-mail I am get it from is the guy Hotmail.  I think maybe he is the problem or he been hacked and does not know it.  But right now I want to stop it from e-mailing from my computer.