Yes, if you have had 6 BBs, I would say that it is a nightmare. That's 5 more than most people have had...
First of all, there is no need for AV for the BlackBerry. There have been no viruses for the BB.
You are not deleting Java. You are deleting Javascript. You can not delete Java.
Has Nextel ensured that your data plan is set up properly?
Frankly, IMHO you are messing around with the BB a little too much. It sounds to me like software issues, possibly self induced. Follow the instructions here -
Main Page - BlackBerryFAQ - to wipe out the BB and load the handheld OS - and do not delete any components or add any third party apps.
Just my opinion...