The browser is likely crashing due to a conflict. Be aware that JRE 6 is only supported for use with Forms 10.1.2.3. I would recommend that you ensure the Forms version has been patched to 10.1.2.3 and I would also recommend uninstalling Jinitiator. If that does not correct the problem, likely the conflict is caused by another browser add-on. This is most commonly caused by an add-on toolbar. For example, Google, Yahoo, MSN, etc. Close ALL open browsers and uninstall the add-on toolbars then reboot and retest.
Also, take a look at the Forms 10 certifications for client side.