Make sure you are up-to-date with all service packs.
Can you give us any clue? Anything unusual? Large dimension?
Turn on SQL Server Profiler trace for Analysis Services.
Send down your request again from Excel 2007 and check the captured MDX manually.
Let us know what happens.
Kalman Toth - Database, Data Warehouse & Business Intelligence Architect
SQL Server Training, SSAS, SSIS, SSRS: http://www.sqlusa.com/