I am currently running Windows 7, IE 8, and have Adobe 10.0 installed on my Dell Inspiron. A few weeks ago I decided to upgrade my IE and figured this is where all of my issues came about. Upon realizing I did not like the updated version I uninstalled and went back to IE 8 and that point I noticed my flash player was not on and redownloaded the program. After this I restarted my computer and noticed flash player did not install correctly. I went through the process of downloading the uninstaller and redownloading, restarted and low and behold it still is not on my computer. I have gone through this process many times, yet everytime I turn off my computer and turn it back on flash player is gone. Today I tried uninstalling Adobe Reader and Flasher player, I redownloaded Reader X 10.1, Adobe Air, Shockwave 11, and Flash Player 10 and 11 while no success. BTW I have tried installing with and without my security protection 32 and 64 bit.
Is your Windows 7 32-bit or 64-bit?
Depending on that, download the appropriate installer from http://forums.adobe.com/thread/909550 and try again.
After the installation is complete, check IE, Tools, add-ons, if Shockwave Flash Object is there and enabled.