Last week, I wasted most of the morning because the WinNT box at my desk (at my consulting gig, thankfully) wouldn't boot. After a while, I found one of the admins, only to find out that the Windows admin was out all week last week. Today, the machine still wouldn't boot (it failed POST). After a few minutes of organ transplants (moving the hard disk around), the problem seems to be the power circuitry on the hard drive.
That's reasonable. Hardware fails, eventually. Of course, there's no backup, but that's pretty common. All of the important stuff is on a Linux server in the server room, which is backed up.
It took a while to get situated on a temporary machine last week. The issue wasn't finding a machine to use -- after one round of layoffs, there are plenty of unused machines floating around the office. The issue was mostly finding a machine that wouldn't crash on login, or prevent software from being installed (damn pesky users trying to get their work done...)