I've been staring at this problem and trying to troubleshoot it for some time now. Whenever I try to compile the .qc of an exported model I get:
SteamStartup() failed: SteamStartup(0xf,0x0012F170) failed with error 1: failed to take master pipe connection lock
with some variant of the "F170" part of the number, and afterward I can't run Source SDK or TF2 (TF2 will give the same error until I restart Steam). It's not a problem with the program, because I am using two different frontends with the same error (GUI Studio MDL and ConText).
I've gone as far as to reinstall both TF2 and Source SDK, though I noticed files remained behind. I may have messed up a file that was not removed when I reinstalled.
If anyone knows this error or knows a way to check my install, I would be very appreciative. I've been wanting to make TF2 items for awhile now, but every time I try to get the compiler working (yes, multiple times) I can't work around it.