That said, the component seems to be very powerful and seems to have many extensions available. Unfortunately, there is an extremely steep learning curve. It also looks like you have to learn a new language (XSL) to customize much of the component.
Adding a basic manual or FAQ would go a long way toward improving this product.
The last time this happened, about a week ago, logs showed that one of the processes used by JCal Pro ([/index.php?optioncom_jcalpro&Itemid3&extmodeday&date200])) was using well over 50% of the server's CPU resources and 7% of the available memory (almost 1 GB). This shut the entire server down almost continuously over a period of several hours until JCal Pro was removed from the system. We've had no problems since then.
On the positive side, JCal Pro is a snap to set up and really looks great. I just wish I could trust it to work properly and not lock the system.
You are using an obsolete version. I recommend an upgrade to the latest stable version.