continual install failure?

[alfresco]

Hi,
Have purchased s3 download version from online shop, and have received email with activation code. I have tried downloading 4 or 5 times now as the install repeatedly fails. "There was an error...." I am using Mac 10.6.8, all up to date, have also run maintenance on eLicencer (previous s2 user) still no go. The install fails in the same place, at Groove Agent- Main, eg 95% through!
Can I download trial version of s3, and then upgrade to full version with my previously purchased activation code??
Any help appreciated