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[quazievil]

I was having similair problems although no where near the time you're talking... smartest thing I did... and I did some pretty dumb stuff... was donwload winEx 5.0 and SEMUv4.1.. unlooped my stuborn card In minutes.

[Chief]

Power your new Mik with a 9V external power supply and put the PS2 cord away, if that's what you're using. Those things are a constant source of trouble.
It most likely is flashed with 6.2 - I'd recommend changing that to UL4s, so you can take advantage of some of the more powerful unlooping utilities that execute in WinEX.
Properly set up and running the right program, you should be able to unloop in under a minute every time, unless you're dealing with a 4B or some other really stubborn card.
I wouldn't advise letting one glitch for 12 hours. Maybe it doesn't hurt the card - but at the least, it's sure a waste of your time.