Having the same Issue here also since the upgrade to 6.0, Windows-XP-SP3 all upto date running ASUS-A7N8X-Deluxe Athlon-3200-Barton 3-Gig ram. I use a download program RegetPro 3.4 that allows for right click context menu from within IE8 to either select a single file download or all from the remote side. I've never had an issue running RegetPro & Avast pre-6.0 without the Sandbox. As the other fellow had mentioned it doesn't matter if you turn off the sandbox feature completely Avast 6.0 will lock the system flat dead, no blue screens or anything else but your only choice is to power off. Again as with the other fellow the only way around this is to turn off Avast 6.0 till I've completed using RegetPro and then re-enable Avast after. There is no other way I've tested it till my systems power switch got hot and I got tired of loading CMD and typing chkdsk /f /x c: and rebooting due to improper shutdowns. I have also uninstalled 6.0 and returned to 5.1.889.0 till I hear other info on this matter.
Thanks for any help in advance,
Hook