Microsoft said it has paused offering downloads of the public test version of its new version of Windows due to "high demand".
The "beta" launch of the highly-anticipated update to Microsoft's Windows franchise began on Friday, but the firm had to halt downloads to add more servers.
"We are adding servers as fast as we can add them," a Microsoft spokesman said at the Consumer Electronics Show in Las Vegas.
He declined to say when Windows 7 downloads would resume.
Microsoft said at CES on Wednesday it would let consumers test the next generation of its computer operating system starting from Friday.