Advanced system utilities to manage, troubleshoot, and diagnose Windows and Linux systems and applications.
Use Process Explorer. Right click on the column headers and add Handle Count from the Process Performance tab.
Sort by handle count and see what process it is. In the lower pane select Handles and scroll through whatever is listed to get an idea of what the program is doing.
On my pc PhoneExperience appears to have some potential handle leak. I just killed the process.