You are right. In the search you can select: [All Time], Last 30 Days, Last 90 Days, Last 6 Months, or Last 12 Months - if I select anything but [All Time] the search will go to an error - it doesn't just report "no subject" - it only "flash" the "loading bar" in right corner for some seconds and stop = no change to screen. If I do select the [All Time] it will process the search and show matching emails as expected.
The date format is set by the langauge selected on the server at installation - it could be US or EN (English) - we would still use the "native" language files.
I just upgraded from SM 3.x to 5.5 - 3.x did not have the "days selection" and we didn't see that problem.
I see no places in the language packs that will work date formats ..
By default the search will take selection "Last 30 days" does any have a solution to make "[All Time]" the prefered selection ? That would help my 400+ users that can't get search to work