Sorry for the very late reply, somehow your post was missed. Did you solve the issue? Have you tried running LW in the tray with screensaver disabled to see if the screensaver is clashing with LW?

Is LW set to run as Administrator?
Have you tried upping LW's running in the program priority list? ie: Control-Alt-Del, Click on Processes & find LW. Right-click on LW & choose a higher priority.
You could also try doing same with screensaver, lowering its priority slightly.

(click to see larger view of sample image)

I have ended up running LW minimized to task bar only, not as a tray function.
I went through the list of options & also stopped it stopping when no downloads were running.
Seems to function ok but it means I cannot run it in the background, only as an operational program.
Painful, when the older versions didn't have this type of fault.