What the Heck is going on here? ... For crying out loud - it's an executable file without an extension! WHY doesn't a knowledgeable Forum Administrator or Opera Software-Developer type chime in with an explanation? Some have made guesses and offered unsupported suggestions, for which they should be thanked, but that's not an explanation! ...
What is "going on here" is that this is an Opera "helps" forum where ordinary Opera users help other Opera users with problems. Sometimes Opera developers may scan forum indices for relevant topics or pass by and chime in, but 'developer' input is not the norm here. Moreover, the thread you resurrected with your post was 10 months dormant, with no further additions until yours.
That having been said, Kaspersky is reporting the file as "legitimate" by itself, but there's something about it that Kaspersky doesn't like - perhaps either the location where it was found or the program contained within the file for some unmentioned reason. Perhaps it's some kind of heuristic-detection thing with Kas... perhaps it's a false positive... perhaps it's a fragment of some malware attack... or perhaps it's a fragment of something shoved at or by Opera when it visited some site. Indeed, Kaspersky is normally a good anti-malware application, but it (like all other security software) has both blind spots and false-alarm potential. The warning it is providing about this file appears to be silent on any real details. At this point, I would suggest submitting the file, if possible, to something online like Viruscan http://www.virscan.org/ and see what they say about it.