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In Windows Vista, Windows XP SP3 and Windows 7, the User Account Control (UAC) is turned on by default. When UAC is turned on, you must explicitly give permission to any program that wants to use "administrator" powers. Any program that tries to use admin powers without your permission will be denied access. To get around this, you should simply right-click on SAP2000 icon and then click on "Run As Administrator..." (or "Run as..." in Windows XP SP3) command and run the program as administrator. You only needs need to do this one time. Thereafter, the program can be run by double-clicking the SAP2000 icon as usual.
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