Not strictly true answers.
Acrobat.com is a mainly subscription web-based multi-app that can be used to file-share, convert formats, save, etc.
Flash and Shockwave are different formats and are used by web-builders in the same way as java is used . to enhance web dispays, advertising, and many other ways. Web sites will work, but you may miss something that does not load.
My advice ... keep flash and shockwave up to date. Switch off flash in browser unless yo need it. This is easy in Firefox, as you can use the plug-in Flashblock to select which sites you allow, and which you do not. For instance, the BBC news site uses Flash to display its videos, as does UTube.
Best way for you is to install the Hosts anti-ad file here ....
http://www.mvps.org/winhelp2002/hosts.htm
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