Hi, Well, i've had a 5 hour session to no avail Have tried F8 last known good config, didn't work Can't get into safe mode Sorry nosirrah, but I don't really have the experience to be doing what you suggested. I made a boot CD with Microsoft Diagnostic tools, allowed me to get in to edit registry, removed a couple of the antivixp08 entries, made no difference. Unfortunately the system has no restore points, which is a pain, otherwise I could have restored it in Diagnostics. Tried a fix by renaming psiapi (or similar), but the "old" copy of file didn't exist on the computer. Ran chkdsk /r, fixed one or more errors, but still doesn't allow me to boot windows XP up. Any other suggestions please? Please note, this computer was running fairly normally and healthily, with the exception of a bit of spyware/malware/etc, before hand. The computer is owned by a middle aged couple who do little untoward on it, mainly just general internet browsing. It was only when the Malwarebytes program was run, trying to repair problems that it had found, that this catastrophic error occured. p.s. I really do not want to have to re-install OS, let alone reformat hard drive, as I cannot really afford to lose any files from the HD.