It was a permissions problem. Win7 comes with a new security system, and I had to add to my profile (even being an admin) this permission: Control panel -> Administrative tools -> Local Security policy -> Local Policies -> User rights Assignment -> Debug programs -> Add user or group . And there, I added my own user. Reboot machine(Important!! Without rebooting, it won't work). After that, I was able to attach processes to debug them. It's been a really long time to solve this, I hope to help other people that find this same problem. Thanks everybody for your help.