The key question is whether the problematic website loads if tried immediately in another browser... if it won't load there as well, it's either a site or a connection/DNS (computer, modem, or ISP) problem of some kind. If it does load, keep refreshing that other browser's page to see if it eventually fails to load there as well. If not and if it provides stable reloads while Opera remains erratic or failing, there is most likely something wrong or erratic with the Opera installation, its stored data, or with its extensions (if any). The idea here is to compare the same site loading behavior with another browser in the same approximate time-frame as the Opera problem occurrence, in order to isolate the cause either to the Opera browser or something external to it.
