Sounds like a bad power supply. Are you using an A1200 or A500 supply? Use a beefier suppply instead. My A500 overheats in about 30 minutes and causes freezing, crashes, etc. It could also be a bad cpu on the accelerator. That 68020 is overclocked and may be damaged as a result. It could also be a dirty edge connector. Try removing the card, cleaning the edge connector with isopropyl alcohol or a pencil eraser, reseat the card and test.