We have a 3 server farm here.. We also had problems with the IMA service dying on us. What it turned out to be was load balancing causing problems. If you have it set to advanced, you will have issues.. set it to basic and it should help. If it already set to basic, I cant help ya much.
We went through 3 months of constant server crashes and freezes untill we saw that, set it to basic all has been well ever since.
Hope this helps.
