Not every unwelcome change is necessarily a fiasco. It's how you handle the transition that determines, to a large extent, whether people perceive it to be a fiasco.
Case in point: Oracle's transition from its creaky but familiar Metalink support site to the new support portal. I'm sure that anyone who has ever been involved in the transition from one web application to its replacement has learned just how many unexpected glitches can creep into the process. Certainly, Oracle has faced similar scenarios, such as when it switched the main corporate web site from a custom-built content management system to a new infrastructure based on Oracle Portal.
Unfortunately, the corporate web site, where people go to find high-level marketing information, is not the same as the support web site, where people go to get problems with mission-critical applications resolved.