Normally the maximum amount recommended with 98se is 512mb although this can be exceeded with memory managers.
Your 384, is this made up with 3 x 128 or 1 x 256 and 1 x 128?
If so then it may be one of the sticks of memory is faulty or not matched with the others. To test this, remove the memory leaving just one stick in the PC and run for a while. If still having problems remove this and try one of the other sticks.
If it runs fine with the one stick of memory then add the other one and see if your machine starts to crash again. This will confirm or eliminate any problems with the memory. Please give this a try and post back with the results. j