Try this. Open the Menu, then click on Account Settings. Click on Synchronization & Storage, and check the settings under Disk Space. Let me know if adjusting these settings helps.

thanks, I have opened sychronization and storage. under disk space synchronize all messages. below that don't delete any messages is checked. I'm not sure what to do next.

re :My inbox says there are 70 messages unread but only the ones received today are showing.

Do you have any filters operating? Check you have these settings:

• View > Folders > 'All'
• View > Threads > 'All'

Check Quick Filter bar: Do you have any of the icons showing a highlight strip of colour ? eg: if the envelope icon has a coloured strip then it will only display unread mail. If yes, one or more icons are selected, click on the icon(s) to remove the filter, so strip of colour is removed.