Struggling

Siebel Systems

(SEBL)

, which changed CEOs twice in just under a year, has lost a key executive, and may have lost one other high-ranking manager.

Eileen McPartland, the company's senior vice president of global services, is leaving the software vendor to take a job at another company, according to a companywide email disclosed to

TheStreet.com

. CEO George Shaheen thanked McPartland for her contribution to the company in the email, but didn't say where she is headed next.

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McPartland's departure is not good news for the company. She developed Siebel's Customer Blueprint program, which makes it easier to for companies to improve the quality of their software deployments. Customer relationship software tends to be large and quite complex, and customers often say they are not getting their money's worth from it.

McPartland worked closely with major customers, and found ways to improve their deployments of Siebel products. With Siebel under intense competitive pressure from

SAP

(SAP) - Get Report

and Salesforce.com, maintaining customer loyalty is absolutely critical.

McPartland, a former executive at SAP who was hired by deposed Siebel CEO Michael Lawrie, was the only female member of the company's eight-member management team.

Another executive who is one rung lower on the management ladder and was a longtime associate of Lawrie is also rumored to have resigned, but his departure could not be independently confirmed.