Some Dell customers were left scratching their heads after Dell sent out a recent firmware update for the company's XPS One desktop systems.

Dell sent out the black CDs over the past few weeks to a "small number" of XPS One customers who purchased the systems with Samsung hard drives, said Dell spokeswoman Anne Camden. Because the systems do not ship with a hard-drive diagnostics system called SMART (Self-Monitoring, Analysis, and Reporting Technology) enabled, the hard drive can eventually go into an auto-scan mode that makes it unrecognizable to the operating system.

There's nothing wrong with the Samsung hard drives themselves, but if users don't install the firmware, there's a risk they will lose access to their data.

The problem is that Dell's update just didn't seem authentic to some customers.

One customer, who asked not to be identified, said he received Dell's firmware CD via courier in March, but something about the package just didn't seem right.

The customer, a chief financial officer at an East Coast investment fund, said he was about to install the software when he had second thoughts. The letter from Dell was on black-and-white letterhead and it was poorly written. He had narrowly avoided being infected by Web-based malware just days earlier. Could this be another attack?

"As I'm pushing it in, I said, 'let me call tech support,'" he said.

First he checked Dell's Web site. There was no mention of the issue.

Then he tried the company's technical support telephone line. After being transferred several times, he finally got an answer from a technician: "He said, 'we didn't send it; throw it away.'"

"Somehow, he reached the one tech guy who did not know anything about this," said Camden.

She would not say how many people have been sent the software, but noted that at least one other customer had "questioned" whether it was legit.

With online scams now a daily threat for most computer users, some simply don't know whom to trust anymore.

Last week, C-level executives were targeted in an e-mail scam in which they were told they'd just been sued. Victims were then sent to a Web page that told them to download an Adobe plug-in, which was actually malware.

"You just start getting a sense that computers are going to get less useable," the CFO said. "I think the whole security thing and identity fraud has people concerned about doing anything."

Dell XPS One customers who have the Samsung drives should have received the firmware update by now, but users who are concerned should call tech support, Camden said.

Hopefully, they'll get the right answer.