I have windows 8 and I had the same problem not too long ago, here's what I did, though it may not work for you.
1. Un-install all the games for windows live crap in your programs.
2. Re-install GFWL from http://www.rockstarg.../PC/GFWLupdate/
3. Find your GTAIV.exe in under C:\Program Files (x86)\Rockstar Games\Grand Theft Auto IV and right-click it, choose compatibility options and set it to Windows Vista SP2.
If you have a 32-bit OS then take the (x86) out of program files.
4. Install patch 4 (nothing newer than patch 4, we'll get to that in a sec) http://www.gamefront...atch_v__1_0_4_0
5. Start up GTA IV. Login/register for GFWL in-game. It will then ask for an update. It will automatically install patch 126.96.36.199
6. Play GTA IV!
Some times you may encounter errors when starting GTA IV after you install mods. ex: "Access Denied" or some crap like that. I fixed this just by running LaunchGTAIV.exe as an admin.
If that does not work, then restart the above steps but download GFWL here instead: http://www.xbox.com/.../DownloadClient
The reason I say download patch 4 is because the other patches didn't want to work for me but patch 4 finally did.
I hope this works for you!