try this:
Force Close:
BlackBerry World - Force Close
I have a similar problem, that, with my 9700, OS5, the browser somtimes will just hang. Progress bar goes to 30% then nothing more will happen, unless I restart.
With this software I can work around the restart. The browser is closed and, afterwars I it is working again.
Does happen about every few days, and, depends on the contents of the web-pages I visit.
I guess, this is a Firmware-problem. If there is a newer one availible for your device, try to make an update. For me, there is no update, and I am happy with the workaround.