With the tracebacks in the output my first guess would be a software error. But there is not enough information here to be sure - it could also be due to a hardware problem.
If you are a registered user on CCO there are tools that can take the output that you posted, along with the output of show version and may give you some insight into the problem. It might also be interesting to run the tool for the output of show stacks.
If it created a crashinfo file, there might be useful information in the crashinfo file to help identify the problem.
If you have a maintenance contract on this router you also have the option of opening a case with TAC and have them help you troubleshoot this issue.