(MONEY Magazine) – Don't be too alarmed by the U.S. Labor Department's announcement that it is investigating 303 companies for possible misuse of 401(k) plan contributions. Most of the nation's 268,000 plans are fraud-free. But if you spot any of the four danger signs noted below, go to your employee-benefits office for an explanation. If you're not satisfied, call the federal Pension and Welfare Benefit Administration at 202-219-8776. This agency's policy is to return your call within one business day. The red flags:

Your quarterly statement consistently arrives late or at odd intervals. If either is the case, your employer could be borrowing or even stealing your money. To find out when your statement is due, ask your benefits counselor.

A significant drop in your account balance can't be explained by normal market fluctuations.

Former employees are having trouble getting their benefits.

The contributions shown on your statement don't match the year-to-date deductions from your paycheck. Companies currently have 90 days to deposit your funds. But if you see a discrepancy, ask.

--Judy Feldman