How Do i Determine What WIndows 7 Process is Currently Using Lots of I/O?

It is generally a bad idea to have more than one antivirus protection system running in your computer.  They do cause conflicts.  In fact, the problem you describe could well be a result of exactly that.  Either use your AV program OR MSE, not both.

Hi Barry,

Poor performance of your computer might have caused by a hardware or software changes. For us to isolate the issue, we would like to ask the following questions:

• Are you experiencing the slowness on a specific program or in a general process?
• Have you made any recent hardware or software changes prior to this issue?
• Can you provide a screenshot of your system information?
  1. Click on Start.
  2. Type System Information, and the press Enter.
  3. Take a screenshot of it and attach it to your reply.

To check CPU usage of every program, you can launch the Windows Task Manager:

1. Press Ctrl +Shift + Esc buttons simultaneously.
2. Click on Processes tab to check the CPU usage.

In the meantime, you can refer to this article on how to optimize Windows for better performance.

Let us know the information about your concern.

Either you're leaving out important information or something really odd is going on with your system.

Instead of concluding that "since MSE runs fine most of the time, another AV could not have been the cause" of the problem of MSE not running, why not simply say that you have no other antivirus or antimalware or security software installed (unless, of course, that wouldn't be an accurate statement)?

If you have Task Manager (and Resource Monitor and Process Explorer) "running all the time," how is it possible that you are unable to state what process is using a large portion of your CPU resources? 

Similarly, Resource Monitor should be able to identify which process has the most disk activity.  For example, the orange line in the graph shows that Malwarebytes Antimalware (mbam.exe) is responsible for the majority of disk I/O (which is to be expected, because it's scanning the system):

Here's what the Resource Monitor graph looks like without the mbam.exe process selected (similar activity, but without the orange line):

I will respond more fully soon, but I did not want to let this problem go without a response from me.  I have the task manager running all the time; it (as well as ResourceMonitor and ProcessExplorer) start automatically when I boot the machine.  I did have a case last Friday afternoon when everything in the system was running slowly (even Solitaire was marked "not responding").  When I saw that MSE was not running, and I could not start it (error code 0x800705b4), I decided that I had to reboot.  I have no idea what was happening, and, obviously, the reboot caused the diagnostic information to disappear.  A Google search of the MSE error code, pointed to a conflict in anti-virus software, but since MSE runs fine most of the time, another AV could not have been the cause.

One more suggestion in addition to Janeane's:

To check CPU usage of every program, you can launch the Windows Task Manager:

1. Right-click on the task bar, choose Properties
2. Click on Processes tab to check the CPU usage.

Once you get Task Manager displayed and have selected the Processes tab, click on the column title  "CPU".  That will change the sequence of the processes displayed to CPU order.  Meaning that the ones that are using the most will be on the top of the list.

Secondly, click on the Performance tab, then Resource monitor to see disk activity (as well as other resources)