Three days after its launch, the BBC's long-awaited iPlayer download service is beset with problems.

More than 900 messages have been posted in the 'Known Bugs and Errors' section of the iPlayer website, mostly by people who have had difficulties installing the software. Some of the posts were made before the iPlayer's beta launch on Friday, but about half were added afterwards.

The types of error reported range from "we are experiencing technical difficulties" to "security update required", "software update required", "delivery service manager has encountered a problem" as well as "licensing" issues.

One user, named 'braddersandscoots', was told, "Sorry, you appear to be outside the UK," to which he or she replied: "I am very definitely in Leeds, West Yorkshire at the moment."

The BBC said today that 100,000 people had registered to use the iPlayer – which allows users to download programs for up to seven days after they have been broadcast – since it went live on Friday.

In a statement, the corporation said: "BBC iPlayer is in beta at the moment and those using it are aware that there are likely to be a few bugs on the service." It said the service is expected to come out of beta testing and have a 'full launch' in the Autumn.

'BillyiPlayer', posting about a "security update required" message he received, said: "Like many others I have the same problem. Have reinstalled stuff and read Help pages to no avail. Wasted an afternoon of my life."

'Trackeditor99', said: "Given this has gone through a lot of beta testing, this is unforgiveable."

The iPlayer relies on a range of different software providers, including Microsoft, which supplies the digital rights management (DRM) program that prevents copying, and Verisign, and it was not immediately clear to today where the source of the problems lay.

One thread in the iPlayer chatroom suggested that the difficulties stemmed from the incompatability of the iPlayer's 'peer-to-peer' component – which connects multiple users' computers together – with that of other TV download services, such as Channel 4's 4oD.

"I've used 4oD a few times in the past with no problem but that seems broken too," said 'Paullewzey', whose error message told him to get in touch with Microsoft.

A BBC moderator in the chatroom, said initially: "It's not for me to give dedicated support, particularly with Microsoft issues, " but later suggested people try uninstalling and reinstalling iPlayer.

"Yup – I get the same error message," 'Yogger' responded.

Some users reported being able to get the service to work by downloading a program called KClean.exe from the internet and then re-installing the iPlayer, but for others even this did not work.

"Braddersandscoots," the Leeds-based user who was told the service was only available to those in the UK, wrote: "What can I do to resolve this problem? Besides moving house..."

More than 15,000 people previously took part in 'closed trials' of the iPlayer, which Mark Thompson, the BBC director general, has hailed as a development as significant as the start of colour TV.

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