virus or download problem?

I take care of computers for a nonprofit organization and one of their users called me about a problem with Avast on his home computer. He said that a notice came up telling him that an update to Avast was available. He likes the program so he clicked the link and it did its thing. Then the computer rebooted and when it came back up nothing worked and there was a circle with a line through it over the Avast icon in the task bar. The cursor would move with his mouse but he could not do anything with his computer. After about 15 minutes a window popped up saying “Deleting”. He called me and I told him to shut down his computer immediately. I was just wondering if this is a known issue. My first thought is that it has to do with his lousy dialup connection and packetloss or some such thing leading to a corrupt file. However I am not sure and figured before I go over there tomorrow that I would ask on this forum. Thanks

Hi and welcome ,
It might be worth your while downloading a copy of the installation file so you have a copy on hand . Personally i would look for other security programs like process guard that have a habit of messing up updates. Zone alarm firewall also has been reported today to have interfered with the latest update .
good luck

Grisbi, without further information it will be difficult to help…
Operational System, Firewall, other security programs installed (specially other antivirus), etc.
Old avast version and new one, etc.