Internet television startup Joost issued a software update on Wednesday after early testers' access was interrupted by a glitch that locked up computers and bombarded them with error messages.

"Our apologies for this — but this is all part of being a beta [test]," Dirk-Willem van Gulik, Joost's chief technology officer, wrote in an e-mail on Wednesday to people testing Joost's service. A beta test is a pre-release or trial version of a product.

Users of the free, advertisement-supported service, currently in closed, invitation-only trials, were bombarded with a stream of error windows alerting them that their digital security certificate had expired.

Joost — the trade name of Netherlands-based Baaima NV's broadcast-quality television service — streams video over the internet through a connection that is encrypted and secured with a digital certificate via a technology known as secure socket layer or SSL.

"As you may know — we use SSL technology to protect your privacy," van Gulik said in his e-mail message, explaining that the certificates need to be renewed roughly every two years. "That moment came, for the first time in our existence, yesterday. Unfortunately we did not realize that we had a copy hardwired into the 0.9.1 client by accident."

He also noted that along with an update of the client software — version 0.9.2, which can be downloaded from Joost's website — the company upgraded its long-term storage servers from which video is streamed to users.

"They are more than [four] times as efficient now. So if you have experienced any stuttering in the past — do try again and tell us if our fixes have worked," he wrote.

Created by the Skype voice-over-internet protocol service founders Niklas Zennstrom and Janus Friis, Joost uses what it calls a "secure, efficient, piracy-proof internet platform" to protect copyrighted content.

The service links what the company calls a "TV-like experience" with the flexibility of the internet by combining it with features such as instant messaging, message boards and news feeds.

In February, Joost is teamed with Viacom Inc. to offer video from the entertainment giant that includes content from MTV Networks, BET Networks and Paramount Pictures, such as reality TV series Laguna Beach, prank show Punk'd, and a mix of recently released and classic feature films from Paramount.