I am aware that similar questions have been posted, and believe me, I have tried a lot of the solutions, but nothing works for me. So I think my case might just be special and deserves a new post.
I'm using Thinkpad T420s, with NVIDIA NVS 4200M graphics card. I installed Ubuntu 12.04 as soon as it came out, but Suspend never worked properly. When I try to resume my computer after suspending it, I just get a lit but black screen. The only thing I'm able to do is to turn off the machine using power button.
At first I thought that's an Ubuntu issue, so I tried Mint instead. However, I was surprised that I met the same problem using Mint: the screen just remains black after being resumed from suspend!
I tried installing pm-utils as many suggested, but it didn't work. I tried installing laptop-mode-tools as many suggested, but it didn't work. I tried installing NVIDIA driver, but it didn't work (weird that I couldn't see any driver in "Additional Drivers" even though I installed the NVIDIA driver). So now I have no idea what to do and am here asking for help.
Thanks a lot for reading this! Any advice will be greatly appreciated.