Is it possible Avast is blocking this download process?
I seriously doubt it. I say this since you did not indicate whether or not there was an avast pop-up.
Is Skype in the exclusions or "trusted" programs in your firewall.
If you use your bank debit card to pay Skype you might find the Skype paysite is a phishing or fraud site.
There have been reports that something fishy is going on with the Skype paysite. I have found Paypal to be very useful.