The software giant claimed that the pre-release versions of Vista are not appropriate for use by a broad, non-technical audience.
"As such, we want to limit the availability of the code to a technical audience, while also keeping the program manageable from a logistical standpoint," Microsoft spokesman Richard Saunders told vnunet.com.
However, the company now claims that the cap on the number of downloads is designed to help it manage the beta test.
"Our goal, especially at this point in the development process, is to make the feedback process as efficient as possible, and we are confident that we will get a high level of quality feedback regardless of the cap," said Saunders.
Dust storm on Titan only the third Solar System body where such storms have been observed
New technique could enable quantum computers to scale-up to millions of qubits
Systrom and Krieger taking time off "to explore our curiosity and creativity"
Comcast's £29.7bn winning bid more than twice the £13.7bn Rupert Murdoch valued Sky at just eight years ago