Check out Tropical Software at
www.tropsoft.com/winvestigator/index.htm
Unless someone has downloaded the trialware version, that someone has gone to some expense to track what employees are doing on those computers.
I would suspect someone "in-house" is doing this rather than an intruder. Do the users of the computers in question hold any "special" position? Does the supervisor of these users by chance have administrator privileges or know the local computer administrator password?
Or just delete/disable the programs and see who complains.
However, since anything is possible, try and determine QUICKLY whether this is an "in-house" problem or not. If you can determine where the logs are being stored (or if they are bing emailed somewhere), this may help with your determination.