Popular social news aggregator Digg prevented individual users and publishers alike from manually submitting new content Monday morning.

The site’s block on manual submissions has since been lifted, but Digg users I’ve spoken to speculated that the move might be part of the company’s ongoing efforts to fix problems that have angered the site’s community. (I’m a frequent Digg user myself.)

On his Twitter account, Digg chief executive Kevin Rose didn’t confirm whether the submission freeze was part of efforts to tinker with the site’s promotion algorithm. (Asked for comment, Digg PR would only point us to Rose’s Twitter account.) He did say that “source diversity” had been an issue thus far. Publisher accounts were in fact allowed to submit via an “auto-submit” function for RSS feeds, but people were not allowed to submit themselves.

Rose pushed out version 4 of the site last Wednesday and was met with a firestorm of criticism over the new vision behind the site, which involves teaming with media outlets and celebrities to create publisher accounts. Users were angered because they saw that primarily publisher accounts had been able to attain “Top News” status on the site.

The new version of Digg has two main issues that give users grief. Thousands of hardcore and casual users have complained about the mountain of error messages that plague them as they tried to go anywhere on the site. There also has been an uproar about the behavior of the site’s “promotion algorithm,” which governs what submissions make it to the “Top News” section. Users have noticed that primarily publisher accounts have been able to make it to that top page. At various points sites such as Mashable dominated the front page, with a majority of the promoted stories.

In an ironic twist, the latest version of this occurred Monday morning when rival social network site Reddit.com got several stories on Digg’s front page at the same time. Some speculated this happened because Reddit fans might be “gaming” the system.

Rose spent much of the weekend talking to unhappy users on Twitter. After receiving hundreds of negative comments last week, Rose decided to bring back several of the more popular version 3 features to the site. They include RSS feeds, more information about when users first signed up for the site, and the return of an “upcoming” section, which would reveal to users which submissions were approaching “Top News” status.