SDK Broken - Fails to start

[thebeanie]

Not sure if this is the correct board, but please move it if it's not.

Source SDK fails to start. I can hit the Launch button, and the small loading window comes up (you know, Preparing To Launch Source SDK), but then nothing happens. Not a speck of activity. Task manager confirms that SDKLauncher.exe isn't running. I really don't know what's causing this.
For the record, I am on 64-bit Windows 7 Home Premium. I've heard that SDK has trouble on 64-bit systems, so I think that might be it. This only affects Source SDK, I can still run Left 4 Dead Authoring Tools just fine.

Can anyone help?

[LFM]

Have you recently updated the SDK or changed any firewall settings? Sometimes if you change your computer's protection settings some programs can go a bit awry.

[BubbleQ]

Or just look if there is some small sdk update lurking around and wont finish it self, kinda happen for me with alien swarm

[thebeanie]

No, SDK appears to be fully updated. I haven't changed firewall settings since I moved onto my new (current) computer, but then again I haven't used SDK since I got the new computer. I think it's the 64-bit thing. Can I force SDK to run in 32-bit or something?