My Rabbit died suddenly and don't know why.The spooky part is his eyes were fully open.Anyone have this happen

My rabbit died just like this last Jan. 17, 2006. I returned home from work one day, and she was just sitting there, quiet in her corner. She was an indoor, uncaged rabbit.....so she could hop anywhere she pleased. By the end of the evening, she had urinated on the floor (before she always used her sand box) and sat in the urine. She woke me up by screaming and making these horrible gasps that night.....and she died in my arms with her eyes open. She was also 3 1/2 years old. The vet said her organs just shut down. All I know....is that I still get teary-eyed talking about it. I'm soooo sorry for your loss.