GreyMagic Software published five security issues for the Opera browser today. Three of these vulnerabilites allow for local file reading, while the last two exposes the users surfing tracks to a malicious programmer.
While all of these are issues to be taken seriously, all can be resolved by disabling Javascript.
One thing that should be noted is this: Opera is still a much more secure browser than Internet Explorer. Internet Explorer has 19 unpatched vulnerabilities, of which eight allow for local file execution, practically giving a malicious programmer total control of the computer.
So, contiue using Opera. If your local BOFH wants to stop you from doing so, due to "security measures" tell him to f**k off and forbid Internet Explorer as well. Or tell him to fix the problem proxyside.