Aggravating, time consuming, and expensive — spam, cyberspeak for junk mail, has gotten so bad that many computers are virtually unusable.

"This is totally illegal and something needs to be done about it," said Peter Chambers of Affinity Web Services (search).

Last year, President Bush signed a law making spam illegal in some cases. The Bush administration has declined to create a national "do not spam" registry to discourage unwanted e-mails, arguing that using the current technology could allow such a registry to be hacked, giving the unscrupulous spammers access to the e-mail addresses on the list.

Spam costs U.S. businesses $4 billion a year in lost productivity alone. Consumers can buy spam blockers for about $50 but larger businesses and Web service providers are spending $1 million or more on software to block certain headers or words in incoming e-mails.

While spammers defend their right to send unwanted e-mail, experts say many of the messages carry viruses, trick consumers into buying useless products at inflated prices and lure consumers into authenticating their addresses and giving up their personal information.

Tech giants Microsoft, AOL, Yahoo and Earthlink are developing "Sender ID," (search) which identifies and deletes any e-mail that can't be traced to its Internet address. It is similar to caller ID for telephones.

Go to the video box near the top of this story to watch a report by FOX News' William La Jeunesse.