Doug and fan. Reinstall with the newest version of TWS, 818.5. (Make sure to install as a user with Administrative rights on your system.)
Do you also have problems logging in? Does TWS keep logging you out or dropping the connection?
Sometimes one of the *.lyt files gets corrupted (I think) and often causes these mysterious problems. A reinstall often fixes things up. (I going to write something up and post it which describes the issue and gives a solution.)
Read your C:\Jts\log.txt file. Does it show any errors?