I run XP SP3 and had several problems that forum users described with 9.1.507.000. I waited a week after the release of 9.1.603.000 to see how things were going for other forum members. The latest version fixed every other problem that I experienced with the prior version EXCEPT IE8 still opens as slow as molasses (15+ seconds) and delays in opening each web page. Yet Firefox opens quickly (2-3 seconds) and responds quickly.
~~snip~~ My installation is about as standard as you can get ... DELL XPS with XP SP3 and MS Office Pro. ~~snip~~
~~snip~~ It is VERY OBVIOUS that something is amiss with ZA and IE8. As everyone else said, I had absolutely no problems with 9.1.008.00.