There are a couple of things that may cause this;
If you are a MySQL repository, then there are times if the console is left up and running which causes the MySQL repository connection to timeout. This is logged in the BMFConsole_Error.log file. I have not seen this happen with other repositories yet, but it a possibility, but check the console error log.
The is an issue which has been fixed in the soon to be released version 7.4 where there is an arithmetic overflow error if the executions, errors, or a couple of other statistics which BMF collects are very large and, when summing the results, the overflow occurs. What version of BMF are you using and what type of results are you getting.
These are the two main issues we have seen to cause this.
Also we have changed the default directories for such things like the error logs to be in the format of //, so unless you overrode the directories, check the error logs in this location.