Sophos 8.0.1c - cannot enable on-access scan

I had this problem too.  Here's how I solved it:

1/Went to Sophos Preferences.  Chose "Live Protection" tab and unchecked "enable live protection".

2/Went to On Access Scanning tab and miraculously it was enabled.

3/Returned to Live Protection tab and checked "enable live protection"

4/Returned to On Access Scanning tab and it remained enabled.

Hope this helps!

Im experiencing the same problem with 2GHz MBP running 10.7.4 and Sophos 8.0.4c. Tried turning off "Enable Live Protection" but it replies with "On-access Scanner failed to set preference". Will try to repair permissions but I think we all need to wait on Sophos for a fix.

Same here. I have 8.0.4c on a brand new iMac. Same issue, none of the above recommendations works.

Just checked my 2009 iMac that is also running 10.7.4 and Sophos 8.0.4c and on-access scan IS enabled. Will compare and investigate differences to find solution.

Just tried doing a custom scan that froze at about 95% done. Quit all applications one by one including Sophos and restarted. Then on relaunching Sophos, on-access scanning is now on. Random?!? or maybe there was permission error thinking I was not Admin that was cleared when I did a full quit and restart.

I'm starting to wonder if this has anything to do with how 10.7 caches memory and re-loads apps on reboot.  Do you normally restore state on restart?

Pardon my ignorance but what is "restore state on restart"?

I don't normally quit all apps before shutting down or restarting if that is what you are asking. I just figured that this time I needed to completely start from fresh. The 10.7 function that remembers what apps were open at shutdown and relaunches them at startup definitely has big pros AND cons - still not used to it!

"restore state on restart" is the function that remembers what apps were open at shutdown and reloads their state at startup -- for apps compiled against the feature.  For apps not compiled against that feature (older apps), 10.7 just relaunches them instead of attempting to restore the state the app was in when the shutdown/restart command was sent.

I am having the same issues as discussed in this thread, with on-access scanning, updating and other Sophos functions not working.

I had a severe problem where my Mac would not reboot properly. Boot up would get as far as Dock, but no application or menu bar, and a permanent beach ball at that point. No ability to access to the user interface. Under direction from Apple Care, preformed the following recovery (which led to some malfunctions in Sophos, 1Password, and no doubt other programs I have not tried yet.)

1. Reboot into Safe Mode (hold Shift until fsck progress bar appears)

2. Delete the contents of the following folders, leaving the folder itself present:

a. /Library/Cache/*

b. /Library/LaunchAgents/*

c. /Library/LaunchDaemons/*

d. /Library/StartupItems/*

e. ~/Library/Caches/*

f. ~/Library/LaunchAgents/*

g. /System/Library/Cache/*

3. Restart back into normal mode

4. Empty the Trash (Important! Do not do this before rebooting, or OS reload will be needed per AppleCare)

This restored the ability to boot, and also seemed to make the OS a bit peppier. However, I started getting error messages from Sophos that it was not running and not updating. I had not noticed these issues before.

Seems that the deleting of listed items could be related, and the astute Sophos engineer should have a great clue in solving the problems discussed in this thread.