The "invalid instruction errata" were made public late last week on the Intel Secrets Web site, which is maintained by Robert Collins.
An Intel spokeswoman in Santa Clara, Calif., said a crash occurs when a user intentionally adds some obscure code to the DOS, Linux, Windows 95 or NT operating systems.
"It's not everyday software," said spokeswoman Luanne Darbonne about the bad code. "The likelihood of an incident [is remote]."
Still, there are tens of millions of installed clients running those operating systems.
Intel, which regularly posts known errata - or bugs - on its Web site was made aware of this latest bug on Friday. It is currently studying the problem and hopes to have a workaround by week's end.
This is the second time this year the Intel Secrets Web site has made Intel aware of a bug in its processors. The first, in May, revolved around Pentium Pro and then-brand-new Pentium II processors. The report exposed a bug that corrupted the way the processors convert integers, a rare calculation required by some applications.