Hmm. Assuming you have the latest drivers (update if you're not sure - it's often the culprit), I think it must be something in your graphics card settings overriding it. I don't think ClearType is responsible (it's not to do with text rendering), but you can always turn it off and see if it helps!
Try making all settings app-controlled, or try resetting to factory default settings. Specifically, the picture editor needs to use point sampling, and something appears to be overriding it to linear sampling. There might be some sampling or filtering setting in your driver changing it. You could also try setting "Sampling" to "Point" in application properties, in Construct.