Recently I've come across this problem as well. I was unable to download the source using TortoiseSVN 1.8, even using my TalendForge account. However, when using TortoiseSVN 1.7 I was able to download it without any errors. It may be because the SVN server software is of an older version?
Hey guys, yea, as kootstra_a just said, if you download an older version of TortoiseSVN or an old SVN plugin for eclipse, the check out works. Very weird.