(There is over 200 gb free on drive)
Where is this free space reported from? Is it accessible from Ubuntu?
You may have more than one partition for Ubuntu, like one for /, one for /home, 1 for swap and so on. If /, /usr, /var and /tmp don't have enough space you can get low disk space errors pretty quickly. Can you open a terminal window and post the output of the command
If you need to free space on / or /var you can empty the apt-get cache with another terminal command
This can free up anywhere from a few MB to several hundred MB depending on how many updates you've installed since the initial installation. Also, if you do any cd/dvd burning look in /tmp for any temporary disc images.
As for reinstalling on a partitioned disk, I'm not sure I understand what you mean because partitioning is part of the installation. If your partition are currently too full the easiest fix might be to reinstall Ubuntu and pay attention when creating partitions.