As far as I know, there are no problems with that combination.
It sounds like you did, but just to make sure:
- Have you compared the IE proxy settings with the ones in avast?
- Are they exactly the same?
If you have, try this:
- Set avast to not use a proxy
- Reboot
- Check if avast still is set to not use a proxy
- Set avast to automaticly use a proxy (the IE one)
- Reboot
- 1) Check if avast has detected the proxy settings.
2) If avast did detect them, check if they are the same as in IE.
3) Try a update (right click avast icon, choose update)
And le me know why you are using a proxy.
Did your ISP tells you to use one or is there another reason?