I/O Error In windows

I have a Athlon 1.4 GHZ Processor machine using a FIC AD11 Motherboard. It has a 256 MB DDR Memory Chip a WD 40.0 GB HD and a Pioneer 106s DVD Drive. I am using windows 98 on the machine currently. The problem I am receiving is that No programs appear to be loading correctly. I do not believe the problem is software related since it occurs on any software I install. I have replaced the Motherboard with no effect. the hard drive and DVD drive including all cables have been swapped out for proven parts With no change. Does anyone have any Ideas? The only two items to be changed are the Processor and the memory chip. Thanks