The USB 2.0 / USB 3.0 thing has nothing to do with SharpCap. A 2.0 version of the ASI120 will not work properly with a USB3.0 port. This is a known limitation of the camera. It is a hardware problem, not a software problem. To correct it, ZWO came out with a 3.0 version of the ASI120, identified by the -S suffix: ASI120MC-S and ASI120MM-S.

Replacing the camera will fix the problem.