My update to Logitech SetPoint v6.61.15 (driver
v5.60.73) actually CAUSES high CPU clocks when my PC screen is locked. I did not have this problem before updating (formerly v6.52.74).
Using an elimination technique, I narrowed the problem down to an interaction between SetPoint v6.61.15 and the Windows 7 Aero themes. When I have an Aero theme active the high-CPU problem happens when my PC screen becomes locked. Process Explorer blames the high CPU clocks on SetPoint.exe. Unlocking the PC screen causes the system to return to normal.