I ran into another error, got frustrated, and played Bloodlines for a bit. Came back, noticed this fix mentioned at HLFallout, and moved/redownloaded (figured it couldn't hurt, I can't play at all as it is). Played a bit more Bloodlines. Finally got to play HL2, after six hours of waiting. I'm glad that there is a fix, but it was really frustrating, after all that ancicipation, and then not being able to play. Hopefully they'll find what's causing the error and put out a small patch, rather than making anyone else redownload.