i was adding a virus program witch was from computer associates and i forgot to take the old one out something happened to my computer so now i can,t get e-mail or use the internet so would anybody know what can be done to save my computer.can some one tell me what does the registry do i down loaded a free registry cleaner  and it is saying i have 150 problems with the registry it only cleaned 20 i don,t seem to have any problem with my computer.

Two antivirus programs on the same computer can cause all sorts of problems.
The registry is where the instructions for your computer are stored. Two antivirus programs mean that both are trying to put instructions in the same place in the registry.
Your best bet is probably to uninstall both programs. Then use Ray's Regvac registry cleaner [you can download a trail version for free].
http://www.superwin.com/regvac.htm
Once you have done this, you can then install the program you want to keep.