Did they all suddenly stop working at the very same time? If they instead variously failed over a period of time, it may be because they've altered their site code to include "browser sniffing" that blocks the old version of Opera (or Opera in general), or else their code has been changed and the old Opera versions simply no longer work with it. Some web sites are always tinkering with their site code to add features, change the displayed layout, etc... and many of them simply don't want to test the new code against all the browsers in the world, so they test with just 2 or 3 of the "biggie" browser names and either block the others or else let them fend for themselves (either working, somewhat working, or outright failing).