Source Sdk crash

I am using Windows 7 pro, and a couple of days ago, source sdk was fully working, now source sdk is pissing me by crashing when i try to open anything like hammer. the -engine ep1/-engine ep2 doesn’t work, and I just want to map. specs: os: windows 7 pro ram: 2.50 GB (2.25GB useable) graphics card: nvidia 6150 se latest drivers installed cpu: Amd athlon 64 3800+ 2.40 GHz.