When using Opera, all hotkeys do things they're not supposed to. Random things. These errors are not present in any other browser or program.
When I select text, then press ctrl + C, the text is unselected when I press the ctrl key. Not every time, only at random.
Ctrl + R sometimes opens the "find in page" bar instead. Not every time, only at random.
Ctrl + F sometimes switches to a random tab. Not every time, only at random.
Ctrl + backspace when writing text sometimes switches to another tab and makes that tab navigate backwards. If only one tab is open, you loose all the text you've written since you leave that page without saving the text.
When I press Ctrl + R the page reloads, but it's not always updated. Sometimes it reloads the page but the reloaded page has the same values as the previously cached page, including the time (on pages that display the time when the page was retrieved). Not every time, so you can never know if you have the updated page or if it just reloaded it from the cache.