That's perfectly normal. Your newsreader keeps a score of which articles you've already read in a newsgroup. Whenever it knows that you've already read an article, it will hide the article from your display the next time you enter the newsgroup. Since you read your own article immediately after posting it, it has disappeared from your view after that.
If someone replies to your article, you'll immediately notice the reply because it will be a new article (which will be shown by your newsreader).
If you have an older Netscape, make sure that all proxy server entries (except the News proxy, leave that one empty) are set to proxy, port number 80. No proxy for: cuci.nl www ftp. Leave the SOCKS Host empty.
If you are using Microsoft's Internet explorer, enable proxy settings and set the proxy server to: http://proxy/
The only way viruses can infect your computer is if you allow a piece of (virus)program to be executed on your computer. By simply looking at a message, this cannot happen. This can only happen if you run a program that was sent as an attachment (like an exe, com, PostScript or macro file).
By the time you want to work online again, you reverse the procedure. I.e. first terminate all Internet programs, then rename the winsock.dll back to mozock.dll, now log in and start the Internet programs again.
The procedure as describe should be fail-safe. Depending on actual configurations and programs used, some steps might be skipped.