According to a Reuters report, Spanish Linux group Hispalinux filed a complaint with the Madrid office of the European Commission (EC) on Tuesday, expressing their grouse against the `Secure Boot' technology which the Windows 8 hardware implements by default.

The report revealed that the Hispalinux group - which comprises 8000 users and developers of the Linux operating system in Spain - has, in its 14-page complaint, called the Secure Boot technology as an "obstruction mechanism."

The complaint, delivered to the EC's Madrid office by lawyer and Hispalinux head Jose Maria Lancho, drew attention to the fact that Microsoft's Secure Boot technology has made it difficult for users of pre-installed Windows 8 computers to switch to Linux and other operating systems.

Going by the complaint, which marks a new challenge to Microsoft after a hefty $731 million fine earlier this month, the Secuer Boot issue being faced by Linux users is rooted in the fact that Windows 8-equipped systems come with Secure Boot enabled in the Unified Extensible Firmware Interface (UEFI); thereby implying that booting will be possible only by operating systems that have an appropriate digital signature.

Noting that users wanting to install another operating system have to seek keys from Microsoft, the Hispalinux group said that Secure Boot was "a de facto technological jail for computer booting systems."

Terming Microsoft's implementation of Secure Boot by default on Windows 8 hardware as an "absolutely anti-competitive move," Lancho told Reuters: "It's really bad for the user and for the European software industry."