Not playing avi
 

When I download an avi formatted movie it does not play right on my player. I can hear the sound fine, but the screen flashes green the whole time and it's impossible to see the movie. I use real player to watch my movies. Please somebody help.

It sounds like a codec issue...

Try installing the VLC media player, it has all the codecs pre-installed and can play just about all files...
VLC media player - Overview

Get one of these pacs also...

For XP this codec pac is very good
Download XP Codec Pack 2.0.8 - XP Codec Pack is one of the most complete codec pack

Or for Vista this pac
Vista Codec Package v4.4.7 Beta 4a (freeware)