I had this problem and tried every .conf file trick I could find. Nothing worked, then someone advised me to just delete my .conf file and try synching without it. At first it seemed like it was not working, but I left my wallet to it's own devices for about an hour and it had synched afterwards.
Try not using a .conf file and just leaving it to run for an hour. Sometimes my wallet is synching but does not show a progress bar and sometimes it does. There have also been times it said it was up to date but then a progress bar appeared showing it was not up to date!
I will leave it for two hours since it is being used on the ultra slow virtualbox Windows XP, we will see what happens. Hopefully it works.Try not using a .conf file and just leaving it to run for an hour. Sometimes my wallet is synching but does not show a progress bar and sometimes it does. There have also been times it said it was up to date but then a progress bar appeared showing it was not up to date!
I hope it's not a problem with virtualbox Windows, because I am not an I.T guy and would not know what complex settings to change, etc.
Will post tonight if mintcoin wallet worked or not.