Apparently one of the wires inside the PSU is getting shorted to ground by the screw. Since this means the insulation on that wire has already been nicked I would recommend you get the PSU replaced. I know it's a pain to RMA something when everything finally seems to be working, but an unshielded live wire inside your PSU with 240V coursing through it is not something you want sitting in your home.
There are lots of places inside a PSU where live current is unshielded, including all the solder points. The thing about them is that they are not likely to get accidently wiggled around or arc to the side of the case of the PSU.
The only "safe" answer is to unplug the thing and wait for the replacement to arrive. To be entirely honest, if I were in your position and I was sure the thing wouldn't get jostled I would probably cross my fingers and use it until the new one arrives. The fact that you have gone through so many fuses indicates that the built-in protection is working as it should.
At the same time, you need to make your decision with a clear idea of the possible consequences. They range from blowing another fuse (possible), to frying one or more (or all) components of your new hardware (less likely), to arcing outside the case and setting something on fire (remote, but still a possibility). I worked for a Master Electrician for four years (doing general building maintenance, not just electrical work) and I know what he'd say.
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The only "safe" answer is to unplug the thing and wait for the replacement to arrive. To be entirely honest, if I were in your position and I was sure the thing wouldn't get jostled I would probably cross my fingers and use it until the new one arrives. The fact that you have gone through so many fuses indicates that the built-in protection is working as it should.
At the same time, you need to make your decision with a clear idea of the possible consequences. They range from blowing another fuse (possible), to frying one or more (or all) components of your new hardware (less likely), to arcing outside the case and setting something on fire (remote, but still a possibility). I worked for a Master Electrician for four years (doing general building maintenance, not just electrical work) and I know what he'd say.