Have you used an older version of LW before? If you have, there might be a preferences folder in the old location (that's point 2 in the fixes sticky)...have a check for that as well. If it's there, delete it.

Did you try changing compatibility to both Win 2000 & NT?

Are you using any antispyware programs? Some will wrongly pick LW as spyware & so it may not open or run. If this is the case, make sure LW's on any list of exceptions/allowed apps or even disable the antispyware & see if LW opens then.