I have Windows Defender but it seems that websites I visit know the signature of certain files and maliciously insert trojans, eg, in files originally from their website but sitting on my hard drive. Are Microsoft aware of this happening, ie not just on an on-demand basis? Thanks

Hi,No idea if that is done however it seems likely you do not have enough protection to detect these early.Windows Defender is an excellent antispyware tool however it is not an antivirus. Try using the methods I use and especially add Prevx to any setup.Here is what I use : Avast and Prevx have proven extremely reliable and compatible with everything I have thrown at them.Microsoft Security Essentials has also proven to be very reliable and compatible.Avast Home Free - stop any shields you do not need except leave Standard, Web, and Network running. Prevx - Home -Free Windows Firewall Windows Defender IE - Protected Mode IE 8 - SmartScreen Filter ON (IE 7 Phishing Filter) I also have IE to always start with InPrivate Filter active if IE 8.(You occasionally have to turn it temporarily off with the little Icon on LEFT of the + bottom right of IE) Avast - Home - Free - stop any shields you do not need except leave Standard, Web, and Network running.(Double ClickBlue icon - details next to OK. - upper left Shields - Terminate those you do not use.)http://www.avast.com/eng/avast_4_home.htmlOr use Microsoft Security Essentials - Freehttp://www.microsoft.com/Security_Essentials/Prevx works well along side Avast or MSEPrevx - Home - Free small, fast, exceptional CLOUD protection, works with other security programs. This is a scanner only, VERY EFFECTIVE, if it finds something come back here or use Google to see how to remove.http://www.prevx.com/ PCmag - Prevx - Editor'a Choicehttp://www.pcmag.com/article2/0,2817,2346862,00.asp Also get Malwarebytes - free - use as scanner only. If you ever suspect malware, and that would be unsual withAvast and Prevx running except for an occasional low level cookie (no big deal), UPDATE it and then run it asa scanner. I have many scanners and they never find anything of note since I started using this setup. http://www.malwarebytes.org/Hope this helps.Rob - Bicycle - Mark Twain said it right.