“Malware or Advertising item was detected by Antivirus’09!” is a popup coming from a rogue security application Antivirus’09. Full message reads:

Downloader.Small-772 is athreat being issued by one of the Antivirus’09 popup on infected computer. Downloader.Small-772 is a non-existent threat, rather a result of self-generated scan by this rogue program. 

“Update Available” is a popup message being issued by rogue program WinPC Antivirus. The message reads:
“Update available. WinPC Antivirus has detected that new threat database is available. Would you like to download and install update now? Installation is recommended.”

“Firewall Warning” is a popup messages created by the bogus security program WinPC Antivirus. Firewall Warning full messages states…

Message Box Object Error is another method for the spammers to mislead computer users into downloading a fake codec or ActiveX Object required to view a multimedia files. The whole message reads:

“Foobar has encountered a problem and needs to close.” is an error report message from computers that got infected by a W32.Relnek.A. The worm is said to crash the computer while it tries to infect the files causing an error message that reads:
Foobar has encountered a problem and needs to close.
We are sorry for the inconvenience.
If [...]

System Protector is issuing a “System Warning” message to get attention of computer users about this rogue program. Computer who have this warning message indicates that they are already infected with a trojan downloader.

“Alert! Your PC is at risk of virus and spyware attack.” is a popup message originating from a trojan that was created to convince computer users to download System Security. The full message reads…