I downloaded Avast5 to a pendrive at the office and installed on my desktop at home without a problem.
When I attempted install on our laptop it says something like “The beta version of Avast System Security has expired go to website…”. System Security was never installed!
no there’s no limit (other than licensing related), how could it be where did you download avast 5 >>> there’s no such thing called Avast System Security. It’s either called Avast “Free”, Avast “Pro”", or Avast “Internet Security”. In all cases version is 5.0. You might have downloaded a rogue, be careful. can you post a screen shot of the install that worked, main software window?
I missed the bit where you said it was a beta, all beta versions were set to expire. Please download what best suits you there: http://www.avast.com/index, “free”, “pro” (trial), “Internet Security” (trial).