Just tried downloading from 2006 and all seems to be OK!
Several possibilities spring to mind
1) start content manager, clear the download list and exit
2) start trainz 2006, click on options and reset the username and password and exit again
3) Perform a database repair - be patient and allow it to finish - do not touch the computer or run any other application - ensure all background tasks are closed or disabled (ie: anti-virus, chat programs, email, etc)
4) restart Content manager and try to download again
Have you recently purchased an FCT? if so has it been activated and have you reset the password (userCP above) as well as in CM?
