Has this happened to you? You're headed to a meeting with your boss, and when you reach his office, you find the corporate attorney and/or HR director with him. The next thing you know, the tag team is telling you: "We no longer need your services", and they're ushering you out the door.

The first time it happens, it can come as a complete shock. But chances are there were early warning signs that indicated your job was in serious danger—warning signs you missed. "I've seen a lot of people get blindsided," says Dan Coffey, a consultant with Spherion who helps executives who've recently lost their jobs find their next one. He estimates that 50 percent of people fired are caught completely off guard when they should have been aware of the evidence against them.

To help you decipher the signals, we've compiled a comprehensive list of red flags. Learn them, and you may be able to take measures to get yourself out of a precarious position—before the only exit route is through the front door while carrying a cardboard box.

1.Your company is sold.

"If your company is sold or your division is sold, you have to realize your job could be affected no matter what level you're at," says Coffey.

Job-saving tip: "Always have your slide deck ready that shows the value you are providing to the firm so that when your company is taken over or you get a new CEO or CFO, you're Johnny-on-the-spot ready to explain your value," says Karen Rubenstrunk, a recruiter with Korn Ferry International. The mistake many professionals make, she says, is waiting for their scheduled meeting with the new management to make their case. "They don't recognize how important it is to make that first impression," she adds. Fail to have your self-promotional sales pitch polished, and you're at the whim of others' perceptions of you.

2.Your company is not making money.

If your company is unprofitable, it's ripe for some kind of change whether it is job cuts, reorganization or the pursuit of a new business strategy, says Coffey. Either way, you have to realize your job may be in jeopardy.

Job-saving tip: Coffey advises professionals to pay particular attention to the way their department is viewed inside their companies for further clues. If their function is viewed as a commodity, the board may decide to outsource the entire department or replace the department head with someone cheaper to cut costs. Either way, start looking for a new job.

3.Your company pursues a strategy you didn't support.

If your company decides to centralize or decentralize, grow through acquisition or divest businesses, and you didn't recommend the move the management team is making, you're going to be perceived as not being on the proverbial bus, or worse, not having the skills necessary to take the company in its new direction.

Job-saving tip: Start making a list of companies that could benefit from your experience, and work on arranging interviews with them.