Entrepreneur Barbara Wein Allen used to have so much faith in her employees that she would loan them company funds to buy homes, cars and other big expenses. But that changed in 2007 when she determined one had stolen an estimated $250,000 from her firm, Multi-Point Communications Inc., a provider of Web- and audio-conferencing services in Birmingham, Ala.

"I trusted her implicitly," says Ms. Wein Allen of the alleged thief, an employee who had worked for Multi-Point for more than seven years in a senior finance position.

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