Hey, folks. The next time you launch TF2, Steam is going to perform a one-time conversion process to upgrade to SteamPipe, a new content delivery system that improves the way content is downloaded, updated and stored. (If you've already upgraded, don't worry, it's done.)
The conversion process will only happen once, and then things are gonna get a lot better. But be patient: The conversion probably will take some time. Even on a machine with a fast hard drive, it could take up to 20-30 minutes, during which time it might look like it's hung. But it's not. Don't interrupt it, just please be patient and let it think.
We're sorry to any of you who are getting subjected to a longer-than-expected conversion time. But ultimately, the benefits will be worth a little inconvenience. You'll get faster uninterrupted downloads, quicker boot times and map loads, and easier distribution, installation and management of mods. Read the FAQ for more info, and thanks again for your patience.