Progress, for lack of a better word, report.
I have downloaded the dotnetfx files, and attempted to repair the installation. 3.5 and 3.0 went well but 2.0 encountered some sort of problem and I have not been able to recreate the ASP.NET User account.
In safe mode (as Administrator) I have been right through Program Files security tabs, and granted myself (as a user) full access to all installed applications.
For all that effort I am still unable to create a pdf from Word, and Nero denies me access. Interestingly it appeared that Nero was going to burn my disc in Safe Mode, I progressed as far as adding the files, which is further than I got in normal mode.
It appears I may need to reinstall, oh joy.
I will only do this if someone can point out what I did wrong last time.
For the record I installed from the XP disc, then installed SP3, and dotnetfx1.1 from my own extra HDD. Having had so much fun with malware recently I installed a firewall and AV software at this point, before going on line to Windows Update for a heapin' helpin' of their latest. (I know this is not the ideal order but I defragged later, just did not want to be on line without protection, its a cold harsh world pout there) How I managed to subsequently install so many apps in such a way as to deny myself access to them is a complete mystery, I only found the ASP.NET user file when I was searching for solutions as to why I was being denied access, I guess it was installed following one of my visits to Windows Update.
I may be eligible for the Guiness Book of Records the way I am going, do Windows Updates give out frequent flyers, or have some other loyalty program?
I am now going to slam the door on my head a few times, the fun just keeps on happening around here.
And just to put the icing on the cake Malwarebytes has denied me access, I don't recall breaking a mirror ...