I first saw this on slashdot.org:

"CNET has a story detailing a new threat to Dell PCs, Apple iMacs and other computers with Intel boards. This has been documented on BadCaps.net for some time, but the article also discusses what to do if you suspect you've got a case of the bad caps."

http://news.com.com/PCs+plagued+by+b...?tag=nefd.lede

Symptoms of bad capacitors are unexpected reboots and shutdowns.