There is a virus that spreads by E-Mail (more details below) and it searches Google (and other search sites) for other E-Mail addresses to send itself to, which apparently caused those search sites to slow down. Using Google is still safe.
"A pesky new variant of the MyDoom worm slammed four popular search engines Monday and continued to clog e-mail accounts around the world.
The new version, variously dubbed MyDoom.m or MyDoom.o, was first detected early Monday morning and quickly went on a tear, flooding many mailboxes with hundreds of messages. It has also slowed Google, Yahoo, AltaVista and Lycos to a crawl because once it infects a PC, the virus automatically performs Web searches on those search engines."