>>>I just added a new message (Update: the sent message to UT also diaappeared )
>>>
>>>and the tree disappeared
>>>
>>> All I see there is a nice globe on grey background
>>
>>As Naomi said, a right click refresh will force the browser to get the new version of the files directly from the server. Unless you have Chrome, I have discovered an issue with that and will be able to tell you what to do to workaround a bug in that browser.
>>
>>To which message did you attach a file?
>i can't even reattach the screenshots from Snagit since it creates png files and UT does not like them

Unless you have a very old version of SnagIt, that's not true. SnagIt can create a lot of file formats, jpg is one of them.