Try this: Help/Troubleshooting, Profile Folder, Open Folder, close TB, delete panacea.dat. Restart TB a few times and see if the state of the folders is the same as when TB was last closed.

http://forums.mozillazine.org/viewtopic.php?p=2764526#p2764526

Hi, thanks for your advice, I tried it but it didn't make the difference, although other details are the same eg if a message was open on closing it will be open on startup, the folders are always expanded even if they were closed at startup. Any other thoughts?

Try deleting or renaming these 3 files, one at a time: session.json (layout and open tabs at last closing), folderTree.json, and xulstore.json (toolbar and button layout; backup before deleting).

http://kb.mozillazine.org/Toolbar_or_windows_layout_not_working

Hi, that didn't work either, if I use safe mode then the folders behave as they should but disabling addons and resetting tool bar and controls doesn't help. Is it worth uninstalling and reinstalling Thunderbird or is there anything else to try? thanks, Martin.

You can uninstall and reinstall, but that won't fix a problem in the profile, that is unaffected by un/reinstall. If it works in safe mode, there are other factors beside add-ons and layout, but I doubt that hardware acceleration is an issue, and you haven't mentioned if you apply a userChrome file.

I would create a new profile, add an account, and see if it works properly. Help/Troubleshooting, about:profiles, to create and manage profiles. The old profile is unaffected, and if the new one works, mail, address books and other data can be transferred from the old profile to the new.

Thank you very much, I will work my way through.

From the main menu bar: Try View (Alt-V) - Threads - Collapse All Threads.

Collapse All Threads and expand all threads are greyed out.

Unless I've misunderstood, the problem is with the folders in the Folder Pane, not the Threads Pane. But if it's the latter, the collapse/expand commands are greyed out unless View/Sort by is Threaded.

Hi, yes the problem is in the folder pane, I have ticked sort by threaded and the threads collapse and expand like good threads should, but the folders go their own way!

One thing I've noticed, if I choose view all folders the problem goes, it's only when I choose view favourite folders that they expand.

re :it's only when I choose view favourite folders that they expand.

I wonder if the expanded view is intentional because you want to see all your favourite folders.

Hi, yes that may be, though I don't actually want to see them all spread out, but perhaps it is a well intentioned feature though undesired.