Avast v4.8 Home and Win7

Hi,
I have two different PCs running Avast v4.8 and Win7.
The first is Win7 64 Home Premium - Outlook refuses to load the Avast plug-in
The second is running Win7 32 HP - Has crashed several times - reported a fault with Avast mail scanner.

Both PCs also report that Avast is reporting its status to Win7 in a “manner that is no longer supported” as a result Win7 keeps reporting that there is no anti virus sw running.

Any suggestions ?
thanks
Steve