The conventional wisdom in Silicon Valley is that MySpace, based in Los Angeles, is a tech nightmare, blaring songs through a user's speakers while crashing all the time. Skilled engineers are in short supply down south, so the website must be falling over all the time, right? Not so. Pingdom, a website-monitoring service, has tracked how often some of the top social networks have gone offline. Twitter, based in Web-savvy San Francisco, has been down for 37 hours from January through April. MySpace has been up 99.96 percent of the time. That's 33 percent less downtime than Yahoo 360, and 60 percent less than Google's Orkut. Score one for the LA crowd. The chart: