I’ve been suffering with a Steam related problem for what seems like forever! The client starts up but will only download from the content servers in little bursts. It will download for about 5 minutes or so and then disconnect, to the point where on an 8mb adsl line it would download all of about 10% of a game over the course of a day!
Finally got around to looking into this this morning before work and found this cunning article tucked away in the Steam Support site. http://support.steampowered.com/kb_article.php?ref=6966-IADH-1503
Turns out that for me at least, deleting my ClientRegistry.blob file and rebooting Steam worked fine! I was getting over 1mb/s download when I left for work. So with any luck this will help out other people who are struggling to get Steam to download their games or updates.