Windows Haning With AGP

My pc was very stable, and hardly ever had a hanging problem. Ever since I’ve installed a Savage4 32MB AGP card, it started hanging. If I put the performance to almost minimum, it becomes more stable, but the quality is poor. I’ve got an Intel Pentium II, 350 MHz with 128 MB Ram. The motherboard model is unfortunately unknown to me. Please help me with this hanging problem.