Well if it was running fine untill you try to use the loader by moveing one of the loader valve controls, I would say that there could be something wrong with the loader valve. If the loader valve is operating properly, it should have a safety that will allow fluid from the pump to bypass an overloaded condition. This bypass is usually right at the input port on the valve. At any rate, a properly functioning valve would remove an overload or blocked condition as soon as the handle was returned to the neutral position. This sounds like two problems with a single component. Not impossible but highly unlikly.
What could be happening is that the changing of the flow through the system when you work a loader control is causing one of the quick connect fittings to "lock up" and stop the flow through the system completely. This could really be a possibility with missmatched quick connectors such as mateing the jinma connectors to connectors made by someone else. You can remove the quick connects from the system entirely and hard plumb the loader valve into the system, or you can unscrew the quick connects off the hoses and from the back side remove the snap ring, spring plate, spring and ball from all 4 of the quick connect components(2 male, 2 female fittings) then re-attach them to their lines and connect them up. This still allows you to easilly remove the loader(engine turned off of course), you will just leak a little oil from the open QC's each time you need to do so. If I recall correctly there was just recently a problem like this on this forum and the person elected to remove the balls and springs from the quick connects and all was fine after that.