I keep getting a nag screen urging me to update from v17 to v18. I downloaded and installed 18 while still keeping my v17. However, when I try to start V18 I get a message that I have exceeded the allowed activations. I have this v17 only on one laptop and one desktop so why cant I update without having to deactivate. I then upgraded the v17 on the laptop and v18 activated but when I tried once more on the desktop I got the same activations exceeded message. I am reluctant to deactivate v17 from my desktop in case the upgrade gives problems.