The last time Albert Haynesworth sat out Redskins practice, he did so because he hadn't passed his conditioning test. Today, he sat out for part of the time because he got sick, according to Rick Maese of the Washington Post.
Maese was told Haynesworth sat out due to heat exhaustion, but Mike Shanahan denied that, saying he wasn't sure what was wrong with Haynesworth. Either way, it doesn't appear that this is a long-term problem.