Older versions of the Prosoft Configuration Builder had a bug that caused the MBTCPUtil Block Index User Defined Data Type to be generated as an INT rather then a DINT, which was not sufficiently large to handle certain calculations. This would occasionally cause a minor Arithmetic Overflow Error. Although the latest version of Prosoft Configuration Builder should no longer generate this error, if you are already experiencing it, this can be fixed by loading up your Compact Logix project, going offline, expanding the User-Defined section under Data Types, double clicking on MBTCPUtil, and then changing the BlockIndex DataType from INT to DINT. After doing so, save and re-download your project, and the error should no longer generate.