tl;dr: Open/close the console once every time you load the game, before you join a server.
Myself, and I know at least 2 of my buddies have seen this happen often enough to be annoying, where the C-bill transfer menu, console, and nametags all become invisible. Clearing the shader cache supposedly fixes it temporarily at least, but that's kind of annoying to do regularly. Anyhow, I'm pretty sure this is a well known issue at this point.
I think I accidentally found a solution. After seeing this issue a few times, every time I loaded the game, I would open the console just to make sure it was working and I wouldn't need to clear my cache. Oddly, after a week, I noticed I hadn't had problems with my console/money menu anymore. Sure enough, the first time I forgot to open my console, my buy menu bugged out. Instead of clearing the cache, I tried just restarting the game, opening/closing the console, then joining the server, and everything worked fine again.
I haven't emptied my shader cache recently, and I can reproduce this behavior 100% of the time on my system at least. Every time I open/close the console after loading, I never have problems. Every time I forget, it bugs out. For reference, I'm running Win 7 x64, MWLL in 64 bit/DX10 mode, windowed.
If you add one line to your autoexec you will never have this problem again.
consoleshow
Works, I tested it all day.