Multiminer suddenly stopped detecting my video card. All of my ASIC miners (ICA) show up just fine, but no OCL any more. I clicked on the "Detect Devices" option but it still isn't seeing my video card. I am able to mine with my card using GUIminer Scrypt, but I want it to be able to automatically switch to the most profitable currency.
My computer did freeze up and I had to reset it when I got home. Since then Multiminer hasn't been seeing my card.
MultiMiner uses cgminer and bfgminer to detect your devices. Which are you using? Try running those from the command line with the -d? argument. If that doesn't list your GPUs MultiMiner won't see them.