Below is a list of valuable threads for Microsoft Security Essentials installation errors and other resources:

• For a check list for installing Microsoft Security Essentials, refer to this thread
• For a List of anti-malware program cleanup/uninstall tools refer to this thread
• For information related to error 0x8004FF07 - Failed Upgrade - Can't uninstall/Reinstall Microsoft Security Essentials refer to this thread
• For information related to Error message 0x8004FF0B and 0x80070715 when you attempt to uninstall or reinstall Microsoft Security Essentials, refer to this thread
• For information regarding Error 0x80070643 when installing Microsoft Security Essentials, refer to this thread