Well try removing the ram module,seems like you have not inserted the module correctly.
Ensure a tight lock between the ram module and slot.In most cases automatic lock occurs when you insert the module correctly.
It may seem more than difficult but try it.
Even after you have had a good locking between the module and the slot and the problem persists then we need to suspect the quality of the new module.
Try installing memtest or other memory checking software and try running it for a few hours if you feel the ram module has some defects.
If you get any errors then probably the new module is a defective one.Ask for a new one.
If you see that there are no errors detected but the system continues to hang then remove all the modules and try running the new ram module only on the first slot and see if system continues to hang.if not then we can suspect that an incompatibility or there is a problem with the ram slot.Try other slots then.