You are rocking a system with an 11 year old CPU. SSE2 instructions are required for Opera 33 and your processor does not support them. Specifically the Athlon XP series of CPUs did not have support for SSE2 because it was developed by Intel and AMD didn't immediately add that feature to all of their CPUs. Sorry mate.

Thank you for the information. Interestingly (for me anyway), not long after my previous post I got a notification to download a "newer version of Opera" (not the newest, but I still get that notification too) that turned out to be Opera 12.17.