Un-installing the browsers wont work, people need to stop jumping the gun and read the thread, theres a lot of duplicate posting going on with suggestions for things he's already tried... I know how much of a pain it can be when you are looking for help and are getting different people suggesting things that were suggested hours/days ago because they havent followed the thread.
Id say its probably a corrput registry for the java/flash installation, the only way to rectify it would be to go through the registry/hard drive and delete absolutely everything to do with the applications, and then re-install them both.
Also, if there is anything wrong with JVM then it can cause no end of problems, the way to combat this is usually to force summit heavy onto the OS like a removal of SP2 and then a re-install of it. Time consuming, but barring that, its probably an OS reload unless ye want to pay an MCSE qualified technician to fix it, would probably solve it in minutes lol.
BTW, I think JVM is now (or soon to be) EOL cos of the monopoly shite so im not sure if Microsoft will offer support with it now but as its a core element of the NT5 OS, they may do? Have you tried contacting Microsoft about the problem, if not, you should, provided you have a legal version of XP, their support teams are actually extremely good and very knowledgeable.