Java SE (Java Platform, Standard Edition)

I'm on my umpteenth attempt at installing this prog, using both the online or offline installers. I've tried all the solutions offered earlier - including uninstalling this and all earlier versions, scrubbing the registry of any mention of "sun" and "java" (followed by reboot), manually registering the dll's and installing to a non-default directory without success. The install registers but crashes at the end of the status with the error "cannot obtain version information from the directory" followed by the usual 1722 error from the package.

System is WinXP SP2 with all updates to yesterday, running IE7, Opera 9.1 and Firefox 2.0.0.1.

Anyone come up with any definitive solutions (other than dumping java in it's entirety - which is very tempting)?