Warning: Some of the items on your 401k menu might be bad for you.

Components of the plan may create a false sense of security, and others might actually do you financial harm.

Don't get me wrong. Investing in a retirement plan is critical to keep you from running out of money late in life. If your employer offers a 401k, then you should take full advantage and start socking away funds now.

But please beware of these four plan features:

Automatic enrollment: A growing number of employers automatically enroll new employees in 401k plans. Thing is, these employees still need to check and make sure that the company 1) puts enough away for a comfortable retirement 2) sets enough aside to collect whatever money the employer makes available to match your contributions 3) invests the money in age-appropriate funds.

Don't be lazy and assume that your employer's automatic plan will provide for a happy retirement. In fact, it's unlikely that your employer's choice works for many employees.

401k loans: Many employers will let you borrow from your 401k plan. When you pay the money back, you pay it to yourself, with interest.

These loans appear attractive because you collect the interest (not the bank), plus they don't require good credit scores. But the best way to secure a carefree retirement is to start saving as soon as possible, keep saving and let compound returns work their magic.

Dipping into your retirement funds for a loan will derail this process. Even worse, if you leave your job before repaying the loan, you'll owe the balance in full. And if you can't pay it, you'll owe penalties and taxes. Yecch.

401k debit cards: These cards just simplify the 401k loan process and allow employees to raid their retirement savings with a swipe of the card. Do you really want to carry this temptation in your wallet? Don't do it. Stay away. Only borrow from your 401k in the direst of situations.

Funds with high fees: Your 401k plan may offer a variety of inexpensive index funds and more expensive actively-managed funds. Always check a fund's fees before investing in it. Manager fees eat into returns and few active funds beat their market indexes over long periods of time.

Some of the smartest investors out there agree that it's best to invest in a diversified group of low-cost index funds. Expensive is not better when it comes to investing.

--Kristen Sullivan