There is nothing you normally do on a windows computer that should cause such problems. You should not have to wait several hours, say a Hebrew prayer of perform a magic incantation. 2004 is defective and needs to be replaced!
In case I was unclear, I've found that the problem OCCURS when leaving the Opera windows open and inactive for a few hours; it's not a solution!
While always accepting (and regretting) that updates contain problems, my purpose is to help to find solutions (or even work-arounds) until the underlying cause of the issue can be fixed.