Try to check the subnet mask in each devices to ensure they are matched. Try to check the gatway and ensure they point to the same devices and the gateway also have corresponding routes (if it will route to other subnet).
Check is there any duplicated address. Check speed, duplex matching.
Don't know the issue of second question, please check if the software require microsoft java machine or sun java. You may require to reinstall the java first then ensure it is included in the path in your PC/server, it makes the java library can be loaded when the problem call it.
Hope this helps.
