I've had the same problems with my serial number. After readings someone else's comment here I did try cut and paste and it worked. Using various search engines I have discovered that many many people are having the same problem. Does it not occur to Lavasoft that if so many people are having the same problem there must be something wrong with their system or their instructions. It is really not good enough to subject so many people to so much trouble and not do anything about it. It is so sad because Ad-Aware does seem to be a really good product but it is being spoilt because they will not address what is clearly a very serious problem.