A bug was discovered that prevented you from opening old rosters created with version 1.10.04b or before. This has now been resolved and it is recommended you upgrade as soon as possible. Unfortunately any rosters created with version 1.11.00b will no longer open in this fixed version since they would have been created with the bug still in place. Your old 1.10.04b rosters should all open fine now however.
My apologies, and many thanks to Hewhowatches on the forums for finding the bug.