I'm having stuff with Steam too. I'm trying to download Garrys Mod for Mac. It worked last night, but now it constantly wants to validate. I removed it, and I can't download it again due to regular "servers too busy" bullstuff which can't be true because I've been trying it for every hour all day and night.
I hate loving Steam. I just want to play my games, I don't want all the other gay stuff that comes with it. I don't want to have to be online all the time (offline mode constantly forgets up and wants me to go online). I wish there was no Steam, and I could just have my games on traditional CD.