So, this is a new piece of malware, which none of the Ad blockers and virus checkers find yet, and only has brief mention on message board postings over last weekend. I managed to find the System32.dll problem by cross referencing DLL calls with registry accesses, and renaming files accordingly. Problem solved.

All I did was click a link in a (in hindsight not very well) disguised spam, so why do I feel like one of those guys who turns up at A&E with a tuba up his rectum, and says "I just fell on it" ?

All IE shortcuts are duly removed from my desktop. Time for bed.