Yes first change the caps out, then possibly the HDD is on its way out as I also had a Power Macintosh 7100/66 that came with dual 230 mb Quantum HDD's. They both worked initially, then, the main HDD started to give me errors. It caused issues as you describe where the machine was working then froze up, a reset would cure it but temporarily. Replacing the Hard Drive cured the issues. My machines have all been re capped.