I have been on my Dell Mini; I suspect the problem was the upgrade route I took from XP-Home -> IE8 Beta ->XP Prof meant the registry was a mess. Repeated re-installation of Flash and Shockwave had no effect.
After much fiddling I fixed it by downgrading to IE7, running the Abode Uninstaller, the installing Flash and upgrading to IE8 again. However I suspect I did not need the IE downgrade first, but I had done this previously.
Hope this saves yo some time.
Read the complete post at http://blogs.blackmarble.co.uk/blogs/rfennell/archive/2008/10/07/flash-problems.aspx