Do you have any toolbar or other helper application that blocks Flash? Some
toolbars that block pop-ups also have a Flash-blocker.
See this site for .reg file to make sure Flash is enabled in the registry:
http://www.kellys-korner-xp.com/xp_tweaks.htm - line 363 on the left.
Download to your desktop and double-click to merge to your registry or right
click and choose Merge - or Edit to see exactly what modifications it will
make to your registry.
Check your security settings - Tools...Internet Options...Security tab,
click Internet Zone, click Custom, and make sure automatic downloads are
enabled. Ensure that "Download Signed ActiveX controls" and "Run ActiveX
controls and plug-ins" are not disabled.
If you are behind a proxy server or are in an administered network
environment - they may be blocking Flash.
If you are trying to install via a web page, try installing via the
downloadable installer:
http://www.macromedia.com/go/full_flashplayer_win_msi or
http://www.macromedia.com/support/flash/ts/documents/killbitblock/flashplayer7_ax.exe
This is a silent installer - you will get no feedback if the install is
successful. You can check for your Flash install status here:
http://www.macromedia.com/software/flash/about/
Tools...Manage Add-ons...change menu to "Add-ons that have been used by IE"
and make sure that "Shockwave ActiveX Control" and "Shockwave Flash Object"
are set to "enabled".
Try posting your issue to the Macromedia Flash support forum:
http://www.macromedia.com/cfusion/webforums/forum/categories.cfm?catid=184&forumid=44
As you'll see, you are not alone in having trouble installing Flash, and
they have support engineers there monitoring the group.