Today I had an issue with the licence file within line 50 going corrupt, so it wouldn’t let me change the activation key to upgrade the program it just kept saying the serial number and activation key combination was incorrect.
To solve this issue you need to rename the licence key file so the program can generate a new one the file is located in the following location.
Windows XP
C:\documents and settings\all users\application data\sage\accounts\2010\sage.usr
Window 7
C:\programdata\sage\accounts\2010\sage.usr