Question:What is wrong with your computer if the hard disk keeps pausing and is in a lag, then resumes operation but has pauses?
Answer: Does the problem occur while using any particular program or process? It may not be the hard drive lagging but could be processor lag if you are doing something the computer can't handle. I would have the Windows Task Manager open while using your computer and see if the CPU or memory spikes when this lag takes place.
If you notice that the hard drive light is flashing often at the same time as the lag then you may want to check your hard drive for fragmentation and run a defrag.
A common cause of having your hard drive work too hard is a lack of RAM. When your computer runs out of RAM it goes to the hard drive for temporary storage. Hard drive memory is much slower than RAM and it can cause a bottleneck in your system.
You should also check your startup items using msconfig to make sure you don't have any unnecessary programs running in the background using resources and slowing your computer down.