When pressing Ctrl+Shift+B in Opera 9.0 to bold something, a new page (tab) opens with the following URL attempted:

< / center> (no spaces)

Didn't test it with Ctrl+Shift+I - it doesn't create the tab with other buttons.

Btw, it'd be better to remove the tags from the code: the buttons need to be on the left for the left-to-right reading people.