Last December 24, 2009, I clicked a link in the Instructables newletter. An alert message box popped up that my computer had malware on it and needed an immediate check for viruses. It offered a free scan of my computer. I clicked OK, the scan detected trojans, and offered to sell me trojan removal software, which I declined to purchase. I spent a lot of time and effort running scans downloading malware removal programs, uninstalling/reinstalling my security program and finally got the trojans removed. I also learned about pop-ups that install the malware on pc's when the pop-up is clicked on. I decided to unsubscibe from the Instructables newsletter, but later relented unwilling to put the blame for the trojans on Instructables. Two days ago, I was copying a recipe from Instructables website. When I clicked on Step 7, a pop-up message from the website appeared that my computer had signs of malware and offered to do a free scan. Being now cautious, I ran a scan from my securtiy that dectected no malware. I clicked "Cancel" on the pop-up to get rid of the message, then did another scan with Malwarebytes. Bam! Infected! I got the security disablers off my computer and then unsubscribed from Instructables newsletter. During the time I was on Instructables website, websites came up without me clicking (while I was trying to copy the recipe. Maybe my cursor randomly passed over an ad, then it came up. I'm thinking the pop-up message came up the same way. I read on McAfee SiteAdvisor comments that this happened to others: a malicious download. Instructables could examine the ads submitted and the instructions submitted for malware. Why aren't they doing that? Why is Instructables website dangerous for malicious downloads?