Looks like it can't work out the format for the last document you had opened.
I had this happen once, but I just went to /home/zaurus/Applications/uqtreader and deleted .openfiles then removed the entry from the LastFile line in /home/zaurus/Settings/uqtreader.conf
Not sure which of the 2 fixed it but it started opening again.
By the way, is there a specific reason you are running uqtreader as root?
Stu