Dealt with.
After some considerations I decided to do another reinstall (which enabled me to fix my miscalculations about assigning disks for XP and Win7) and now Java behaves as expected.
Exactly the reason why programs like tweakUI should not be used....
Oh dear, you mean the few hundred times I used it before in its various incarnations I just got
lucky?
I never said it failed 100% of the time
Just the problems it can cause are usually a nightmare as you don't know what the program has done in the background.
TweakUI is easier then registry hacking (it basically is a borderline registry hacking tool, just one made by Microsoft).
True, but if registry changes are needed to configure something, my recommendation would be to learn exactly what needs changing, and do it properly, not just use a tool to do it, which ultimately could do anything.....