Please ask your school to install something newer (e.g. IC615).
In general there was no problem witht the calculator in this release (because it's a vital part of the flow). However, there may be some issue with either your environment or with the specific expression which is causing something to crash and hence it can't talk to the Java process.
I did some searching, and there's no general problem reported that allows me to debug easily. A few specific issues related to large data causing it to run out of memory, but nothing general.